US Cryptologic History Series VI, Vol. 2 - Purple Dragon

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NO. 609

CCH-E32-93-04

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PIJRPLE D R A G O ~ :The

Origin and Development

of

theUnited States OPSEC Program

united states cryptologic history

I HIS DOCQlvlENI CON IAiN5 C O " ~ V V O ~ O r v l t f f E ~ I A Lr ~ e T ~ E L E A ~ A I ; L E TO f i e ~ E I C ! l r ~ r ~ t ( T I O r ~ A L 5

Classified by: NSAlCSSM 123-2

Declassify On: Originat ing Agency's Determinat ion Required



This monograph is a product of th e National Security Agency historyprogram. Its contents an d conclusions ar e those of t he au th o r, b ased onoriginal research, and do no t necessarily represent th e official views ofth e National Security Agency. Please ad dr ess d iv erg ent opinion or

additional detail to the Ce n te r f or CryptoJogic History (E324).

Contents of this publication should not be reproduced or further disseminated outside th e U.S. Intelligence

Community without the permission of th e Director, NSA. Inquiries about reproduction an d dissemination

should be directed to th e Center for Cryptologic History, National Security Agency, Fort George G. Meade,

MD 20755-6000, ATTN: E324.



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UNITED STATES CRYPTOLOGICHISTORY

Series VI

The NSA Period

Volume 2

PURPLE DRAGON:

The Origin and Development ofthe United States OPSEC Program

(b ) ( 3 ) -P .L . 86-36

CENTER FOR CRYPTOLOGIC HISTORY

NATIONAL SECURITY AGENCY

1993

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Table of Contents

Page

Foreword v

Acknowledgment Vll

Southeast Asia Map ix

Part I: Introduction 1

Part II: The Beginnings OfOPSEC 7

Part III: PC"RPLE DRAGON atWar 35

Part IV: NSA and PC"RPLE DRAGON 57

Part V: What Charlie Knew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Part VI: OPSEC Goes Worldwide .

Part VII: PURPLE DRAGON at Peace .

. 75

. 89

Author's Biography 94

Abbreviations and Covernames.. 95

Bibliography 99

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Foreword

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Operations Security (OPSEC) as a concept is probably as-old as/war $tself.

Nevertheless, the fact that poor OPSEC practices have/been costly in loss of

human life and l os t obj ec ti ve s in every American war demonstrates. that,despite its venerated age , Ope ra ti ons Security/as a doctrine needs Fto be

learned afresh by each generation.

I t is imperative that thos e w ith r espons ib ili ty for.: military activi t ies

understand that observat ion of Operat ions Secur ity principles is as essential an

ingredient to victory as any of theother tools of war.vTo the extent possible,

these lessons should be learned in peacetime -- experience in recent conflicts

shows there is unlikely JO be a period of grace once a military emergency

occurs and troops are committed to combat.

I lin PURPLE DRAGON: The Origin and Deveiopmeii: of theUnited States OPSEC Program has given US a superb monograph about the

genesis of Operat ions Securi ty during the Vietnam War.llthoroughand re ad ab le accoun t describes th e in itial problems in air operattons which

prompted a high-level investigation, explains the weaknesses in U.S. practices

which this investigation identified, shows how Operations Security principles

were developed through c lo se analys is o f the problems and weaknesses, and ,

finally, tells how Operat ions Secur ity at l as t became ins ti tu ti onal iz ed . Of

primary importancej Ishows clearly that complacency is dangerous,

not only before th e principles of Operations Security have been applied, but

even after , as situations evolve, personnel change, and the adversary

undertakes new intelligence initiatives.

The Center for Cryptologic History believes t h a ~ Fonograph is

an important addition to the study of cryptologic nIstory and, mdeed, to the

l i terature on the Vietnam War. I t has much to sa y to two audiences: those

unfamil ia r with Ope ra ti ons Secur it y will find it a good introduction to the

concepts and methodology of this important component. Those already

fami liar wi th Operations Security should f ind it an in te res ting study of OPSEC

origins as well as a refresher on th e basic princ ip les o f the discipline.

This story of PURPLE DRAGON is not just for the military; its lessons

apply to the civilian cryptologic professional as well. The Center for

Cryptologic History hopes that this study will reinforce the impor tance of the

doctrine and help us to examine ou r premises and practices, military and

civilian alike.

DAVID A.

HATCHDirector,

Center for Cryptologic History

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Acknowledgments

(U) I wish to take th i s oppo rtrun i ty./ to thank \.evetyone

who con tr ibu ted to the product ion of th i s monograph.

F i r s t , I would l ike to thank a l l those / who q r ac i ou s-Ly

consented to speak wi t h me concerning t he i r e x p e r iences

with PURPLE DRAGON and OPSEC, especiallyl. IL...- .".....---.,,...-.,,..,.._---...Iandl . Ii The ira s s i s t ance

was t r u ly indispensable . I Mould also l ike to express my

gra t i tude to the employees of th e NSA archives .

(U) I would also 1 ike to thank those who read the

dra f t of th i s paper , reviewing it fo r factuaV content and

s t y l i s t i c reasons . Among those who provided va luable

sugges t ions , I pa r t i cu l a r ly wish to thank Milton Zaslow,

__________Iand NSA's Office of Operat ions Secur i ty .

(U) Spec ia l thanks must go to David Hatch and Hen' r y

Schorreck, the cur ren t and former His tor ians of th e

Nat iona l Secur i ty Agency, and th e other members of t he

Center fo r Cryp to log ic His tory fo r g iv ing me the

o pp or tu nity to produce th i s paper and fo r pu t t ing up with

me whi le I worked on it.I I

my ed i to r a t

the Center , deserves spec ia l thanks fo r her e f fo r t s in

making the f in ished product presen tab le .

(U) Fina l ly , spec ia l thanks t .ol---------- . . . . . ,withou t whom I never would have/undertaken th i s pro j e c t .

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Part I

Introduction

WHYOPSEC?

CD) Throughout the history of armed conflict, a few general tactical rules have directed

the actions of armies around the world: control the high ground; preserve your supply

lines; and, most of all, maintain the element of surprise.

CD) Generals have always recognized that tactical surprise is one of the most effective

force multipliers available to them. Because of this, one of the primary objectives of every

military campaign is to strike when and where the enemy least expects it and before he

can take defensive measures. As the Chinese general Sun Tzu, writing in the fifth century

S.C.E., advised, "Take advantage of the enemy's unpreparedness; travel by unexpected

routes and strike him where he has taken no precautions." Another Chinese general, TuMu, said of Sun Tzu's advice, "This summarizes the essential nature of war ... and the

ultimate of generalship." 1

CD) In the twenty-five centuries since Sun Tzu, military history has been reple te with

examples of battles that were won in large part because an at tacking army was able to

maintain the element of tactical surprise. One battle, the first battle of Trenton during the

American Revolution, can stand as a classic example of the benefits of tactical surprise.

CD) Following a successful campaign in New York and New Jersey dur ing the summer

and fall of 1776, the commander of British forces in North America, Si r William Howe,

decided in early December to suspend operations for the winter. British troops and their

Hessian mercenaries were therefore bivouacked in a series of outposts acrossI \

ew Jersey.Bivouacked in Trenton were three Hessian regiments, plus miscellaneous troops and

artillery under the command of Colonel Johann Rall - in all, about 1,400 men. Although

instructed to build defenses for his t roops, Rall, convinced that the Continental Army

posed no threat to his position, merely established sentry posts throughout the town.

CD) On Christmas night 1776, while Rall and h is men celebrated with extra rations of

rum, General George Washington set in motion one of the great surprise a t tacks in

mili tary annals. After ferrying across th e Delaware River , which the British and

Hessians deemed impassable due to floe ice, the Continental Army marched all night

through the snow and, by dawn, 26 December, had managed to surround RaIl's troops on

three sides. Surprise was so complete that the f irst evidence the Hessians had that the

Continental Army was even on the move came when a sentry on the nor th side of Trenton

caught a glimpse of the main Continental force on the edge of town. Before he could raise

the alarm, the Continentals attacked. In the forty-five-minute battle that followed, RaIl

was killed while trying to rally his disorganized and unprepa red t roops, and the

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Continental Army captured more than 900 prisoners, as well as large stores of arms,

ammunition, and provisions. American losses were negligible. 2

(U) While history shows many instances of battles like Trenton, won because an

attacking armymaintained the element of surprise, it is equally full of examples of battIes

lost by the failure to maintain surprise. An example of this, also from the American

Revolution, was the British march on Lexington and Concord on 19 April 1775.

(U) Based on intelligence that the Massachusetts Provincial Congress was gathering

military stores in the town of Concord, the royal governor, General Thomas Gage, decided

to send a troop of approximately 700 light infantry and grenadiers to Concord to destroy

them. Gage's actions, however, soon gave his plan away.

(U) Beginning on 14 April, Gage relieved the grenadiers and light infantry from their

regular duties, ostensibly for training in new drill and maneuvers. Furthermore, on 15

April all of the long boats and barges of the Bri ti sh t ransports in Boston harbor were

transferred to shore.

(U) These events did not go unnoticed by the populace of Boston. On 15 April, Joseph

Warren, the pat riot l eader in the city, dispatched Paul Revere to Lexington to notify

Samuel Adams and John Hancock of the developments . Word of the British actions also

spread to Concord, where townspeople began removing the military stores to Worcester,

further inland. On his return to Boston, Revere also met with Colonel William Conant of

the Massachusetts militia in Charlestown and agreed to establish a signal in Boston's Old

North Church which would indicate when the Brit ish troops began to move and whether

they were crossing to the mainland by way of Boston Neck or crossing directly over the

Charles River.

(U) The situation in Boston remained tense bu t quiet for the next two days, bu t on 18

April the HMS Somerset, without warning, was moved from its moorage in Boston harbor

to a position at the mouth of the Charles River, where it would be able to control the ferry

between Boston and Charlestown. General Gage also dispatched small squadrons of troops

in the late afternoon to patrol the roads between Boston and Concord and prevent any

messengers from getting through, and he ordered the sentries at Boston Neck to challenge

anyone trying to leave the city. Finally, in the. early evening, the l ight infantry and the

grenadiers began to quietly assemble at the foot of Boston Common, on the banks of the

Charles. By eleven o'clock, the first troops had begun to embark for Charlestown.

(U) The implications were clear. Warren dispatched Revere and William Dawes to

ride to Lexington and notify Adams and Hancock to escape, in case their capture was the

object of the British troops. Revere and Dawes were also to rally the local militias andhave them muster at Concord, in case the military stores were the British objective.

Before setting out, however, Revere had two lanterns hung in the Old North Church's

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spire to notify the milit ias on the northern and western banks of the Charles that the

British were coming.

(U) The two riders then se t out. Revere lef t Boston by rowing across' the Charles right

under the guns of the Somerset, apparently without being detected. Dawes, meanwhile,

somehow managed to convince the sentry on duty at Boston Neck to le t him pass. Anyway,they both managed to get out of Boston and, as the famous poem relates it , to spread the

word to everyMiddlesex village and farm.

(U) By the time the British troops arrived in Lexington on the morning of 19 April,

they did not find Adams and Hancock. They did find a small body ofmilitia on Lexington

Green. A quick skirmish put the milit iamen to rout, and the British were soon on the

march again to Concord.

(U) At Concord the British found and destroyed most of the mili tary stores still in the

town. They also found a larger body of local militia, with more coming all the time. The

British confronted, and were defeated by, the militia at Concord's North Bridge. Sensing

that the situation was, or soon would be, desperate, the British began the long retreat backto Boston. The retreating column came under constant harassment from the militiamen,

suffering heavy losses, and only the arrival of 1,200 reinforcements from Boston saved the

original column from destruction. The Brit ish troops faced heavy fire all the way back to

the Charles River, where the guns of the fleet in Boston harbor finally convinced the

militiamen to cease their attack.

(U) The Brit ish would remain besieged in Boston until the followingMarch." The first

day of the American Revolution thus ended in a stunning upset as one of the most

professional a rmies in the world , wel l armed and well trained, was routed by a

disorganized rabble of farmers and tradesmen, most of whom had never fired a shot in

anger before in their lives. And all because the Brit ish could not keep their intentions a

secret.

(U) As Washington himself wrote in 1777, "upon secrecy, success depends in most

enterprises . . . , and for want of it , they are generally defeated, however well planned and

promising a favorable issue." 4 From the Revolution to the present, the United States ha s

made a concerted effort, through such means as physical security, cryptography, and

counterintelligence, to keep information concerning its intentions and capabilities from

falling into the hands of it s enemies during wartime.

VIETNAMASAN OPSEC CATALYST

(U) Bu t while the benefits of maintaining the e lement o f surprise as a military

objective, and the dangers of losing that surprise, have always existed and have been

recognized as vital to tactical, and even strategic, success, it was only dur ing the war in

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Vietnam that the United States began to make a concerted effort to review it s security

posture from the vantage point of an adversary in order to identify that information

concerning U.S. intentions and capabilities that an adversary considers vital, to discover

how he gains such knowledge about U.S. military plans and capabilities, and, finally, to

develop strategies by which U.S. commanders could prevent h im from gaining that

knowledge. This "ability to keep knowledge of our s trengths and weaknesses away from

hostile forces'" became known as operations security, or OPSEC, and had its birth in an

operation known as PURPLE DRAGON.

(U) Early in its involvement in Vietnam, the U.S. military came to the realization that

several of i ts operations were not being fully successful. Enemy forces were somehow

consistently able to avoid the worst consequences of U.S. and Allied operations, and senior

U.S. commanders wanted to know why. Assuming that North Vietnam and the Viet Cong

were not l ikely to be decrypting the United States' most secure communications and that

they could not have enough spies in South Vietnam to be aware of every U.S. operation in

Southeast Asia before they took place, U.S. personnel came to the conclusion that U.S.

forces were themselves inadvertently revealing vital information to the enemy.

(L'") To test this hypothesis, the U.S. Joint Chiefs of Staff authorized Operation Pl:RPLE

DRAGON. Relying on a multidisciplinary investigation of al l aspects of combat operations,

from conception to planning to execution, the men of PURPLE DRAGON sought to uncover

those elements of an operation which might be insecure and which of those elements might

be able to provide valuable, exploitable information to the enemy. Once uncovered,

PURPLE DRAGON could then suggest possible remedies for those elements to the concerned

commanders in the field.

(C) From it s inception in 1966 and 1967, PURPLE DRAGON proved a major success at

improving the combat effectiveness of t he uni ts and operations it surveyed. PURPLE

DRAGON was so successful , in fact, that before the war was over the Joint Staff madeoperations security programs, based on the PURPLE DRAGON model, mandatory for al l U.S.

commands everywhere in the world. Operations security would prove so successful in the

end that President Ronald Reagan would make it a requirement for every U.S.

government department or agency, military and civilian, with a national security mission.

(U) It is the goal of this study to explore why and how operations security in general

and PURPLE DRAGON in particular came about. It will attempt, furthermore, to show how

the concept and methodology of OPSEC were developed; how OPSEC came to prove itself in

the rice paddies and jungles of Vietnam; how it came to win acceptance, f irst among the

U.S. military in Southeast Asia and the U.S. Pacific Command, then by the U.S. military

establishment worldwide; and, at last, how operations security came to become an official

policy of the Uni ted States government. Final ly, it will seek to document the vital role

that the National Security Agency has played in the development of operations security,

from the birth ofOPSEC during the conflict in Vietnam to the present day.

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Notes

1. (U) Sun Tzu. The Art ofWar. Trans. Samuel B.Griffith. (London: Oxford University Press 1963),134.

2. (U) Bruce Lancaster. The American Revolution. (New York: The American Heritage Library, 19711, 161-166;

Willard M.Wallace. Appeal to Arms: A Militory History of the American Revolution. (Chicago: Quadrangle Books,

1951), 127-131.

3. (U ) Lancaster. 84-91;Wallace, 12-26.

4. (U) George Washington, letter to Col. Elias Dayton, 26 July 1777 ,quoted in Jack Ingram, "Historical Impact of

OPSEC onMilitary Operations" (NSA Video) (FOtJO>.

5. (U) William O. Studeman. "Cryptologic Orientation Welcome Address" (National Security Agency Video TVC

1984,1989) rsi

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Part II

The Beginnings ofOPSEC

WHY PURPLE DRAGON?

CU) On 7 February 1965, a Viet Cong CVC) platoon attacked the U.S. air base at Pleiku,

about 200 miles north of Saigon, in the Republic of Vietnam CRVN or South Vietnam).

During the attack, the VC destroyed one transport aircraft and nine helicopters and

damaged fif teen other aircraft. They a lso b lew up a barracks, killing eight U.S.

servicemen while wounding 126 more.

CU) In response to the Pleiku attack, President Lyndon Johnson approved a proposal

for continuing ai r s tr ikes against targets in the Democratic Republic of Vietnam (DRV or

North Vietnam), as opposed to the policy of quid pro quo retaliations for North Vietnamese

attacks that had been in effect since the Tonkin Gulf incident of August 1964. The first

raid under the new policy took p lace on 11 February 1965, when 160 U.S. and RVN Air

Force and Navy fighter-bombers struck targets north of the 17th parallel, the official

boundary between the two countries. The policy of continuing ai r strikes north of the 17th

parallel, to be carried ou t by fighter-bomber aircraft, was given the covername Operation

ROLLING THl:NDER. 1

(U) On 17 June 1965, U.S. B-52 bombers from Andersen Air Force Base in Guam for

the f ir st t ime launched a mission against a VC stronghold in South Vietnam. Thi s and

future B-52 missions from bases in Guam, Okinawa, and Thailand were covernamed

Operation ARC LIGHT.2 From that time on, ARC LIGHT s tr ikes aga inst VC and North

Vietnamese Army (NVA) targets in South Vietnam and ROLLING THUNDER strikes against

targets in North Vietnam became an almost daily occurrence.CU) By the summer of 1966, however, it had become clear that the bombing missions

were not having as significant an effect on the VCINVA as had been expected. Ground

sweeps and bomb damage assessments of B-52 target areas discovered lighter enemy

losses, in both men and mater ia l, than expected, and North Vietnamese infiltration of

more men and material into South Vietnam was apparently not being inhibited by air

strikes in the DRV. Morale in the VCINVA still seemed high after a year of bombing, and

North Vietnamese military and industrial activity did not seem to have been severely

hampered." The concern was on many people's minds - was U.S. intelligence concerning

the enemy's whereabouts and strength faulty or, more ominously, were the the ARC LIGHT

and ROLLING THUNDER missions being given away in advance, providing the VC/NVA the

opportunity to avoid them?

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President Lyndon B. Johnson and

General Earle Wheeler, USAF, Chairman of th e Joint Chiefs of Staff

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The final proofof the meaningIr-----,.....-"""":"'""""":"'"--:---=-:-:::"""":'----:-:---........---:---:-!......

---'came during the U.S. bombing moratorium between 24 December 1965 and3.1 January 1966. The messages.stopped along withthe......•b.ombing. Ry early 1966, theanalysts at NSA were able to sho1 ... ..... Ito between 80 and

90 percent of al l ROLLING THUNDER missions. to

~ A f t e r performingmore analysis of the l inks betweeni land ROLLING

THUNDER durin the earl part of 1966, 821 finally released a re ar t of it s findin sin Ma

detailin The effect was immediate.

821, had uncovered evidence of Chinese forces in~ ' : " " " " ~ - : - : : - : - - " " ' " " ' " ~ " " " : " ' : = ~ ~ ~ - - - : ~ - - - : , ~North V i e t n a n i ( C F ~ V N ) and had begun full-time monitoring of manual/morse code

communications between

I land the CFNVN. Fo rseveral months these communications consisted of short, formulaic messa es

""\rSCl..Play'ing a hunch byE. Leigh Sawyer, t hen chief of B21, analysts began

comparing thel I m e s s ~ g : e . s against.U.S. operations in Southeast Asia. They

discovered an apparent match between the(/ Imessages and some ROLLING

.......U o . l o . : ~ . w . I O o , I A . . ~ · s s i o n s . Upon further analysis,Jhey discovered a near perfect match between

nd lanned ROLLING THUNDE.Rmissionsover the northeast uadrant of Korth

;.....

B21 also produced another four reports on' r - - . . . . . , . . - - - - ~ _ : _ - " " " " : " ' " " " " " : " " ' : - - - ~ 1....-__ .....

messages, their probable content, and their relationship to ROLLING THUNDER"----:---:-'

missions, during the course of the next three months. Leigh Sawyer gave a private

briefing onl Ito General EarleWheeler, chairman ofthe JCS. After the briefing,

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according to Sawyer, Wheeler's only response was to slam his fis t on the desk and shout,

"Goddam it, we've been penetrated!" 11

('fOC UP) :At the same t ime as it s findings onl INSA was' uncovering other

evidence of hostile prior knowledge of U.S. air operations in Southeast Asia. The Strategic

Air Command (SAC) had begun overflights of North Vietnamese and Chinese territories

using low altitude photographic reconnaissance drones in 1964, covernamed BLUE SPRINGS

in 1966 and redesignated at various times BUMBLE BUG, BUMPY ACTION, and BUFFALO

HUNTER. C-130 mother ships operating out of Bien Hoa ai r base in South Vietnam would

release the drones over Laos or the Gulf of Tonkin; the drones would overfly northern

North Vietnam and then b r cov r d over the Gulf b helico ters 0 eratin out of D

Nan ,

"'PGG)..L'iSA had a l s 6 u n c o v e r e d e Y i d e n c e u o f ~ o r t h Vietnamese alertin of ARC LIGHT

missions dating back at least to late 1965. These alerts,

were issued on 34 percent of B-52 strikes during 1966, with an....._----.....,.-""':"""".....

average warning time of eight and a half hours. Though usually general in nature, theVietnamese alerts did occasionally include detailed targeting information.13

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Director, National Security Agency

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(U) The problem with monitoring, however, was that COMSEC monitoring, by it s very

nature, was selective, the findings being limited by the fact that the SeAs cou ld not

monitor all communications all the time. Monitoring, furthermore, could uncover COMSEC

lapses only after they had occurred. 19

b) ( 3 ) -P .L . 86-36

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BIRTH OF THE DRAGON

-tTSfAt the beginning of the PURPLE DRAGON survey in December 1966, the surveyteams lacked clear guidance on what they were looking for and how to proceed. However,

following a briefing from CINCPAC on the sort of information they were to seek, and

improvising as they went along, the PURPLE DRAGON teams and staff were able to develop

an efficient method for both the gathering and the analysis of information on potential

sources ofenemy foreknowledge and forewarning. The PURPLE DRAGON teams decided that

the fundamental process of the surveys would be to "put ourselves in the position of the

adversary and s tudy our operations step by s tep, from concept ion through execution to

completion and beyond." Furthermore, they would focus their attention on the small,

seemingly insignificant details of the surveyed operation, considering them to be just as

likely, i f not more so, to provide valuable information to the enemy as the major aspects of

the operation."

kSrThe PURPLE DRAGON survey teams' f irst order of business was to develop a complete

overview of the operat ion and of each mission in that operation. Though already

knowledgeable about the operations they were to survey, the teams began by reviewing

"operations o rder s and directives, communications-electronics operating instructions,

pertinent COMSEC .. .and such other documentation" so that they would be as familiar as

possible with "the details and possible weaknesses of the operation before

commencing. . . . " 35

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U.S. Ai r Force CH·53 helicopter recovering a

BLUE SPRINGS reconnaissance drone over the Gulf ofTonkin

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i r Combat

~ N'l'J On being apprised of PURPLE DRAGON's findings c ~ n c e r ~ i n ~ L . : - ~ ~ _ - - - - J11 I fSAC began to upgrade it s worldwide operations

codes, ByTJUije1967, land, by the

following spring, two I I had been

introduced. Also as a result of PURPLE DRAGON, CINCPAC ordered the installation of aKW-26 secure teletype link between Bien Hoa and Da Nang to handle BLUE SPRINGS

t raff ic. In fact, the KW-26 was on-line between Bien Hoa and Da Nang within a week after

CINCPAC's J-6 was apprised of the situation. The KW-26 l ink was s ti ll later replaced by

an HY-2/KG-13 secure voice link between the two bases. 50

"'t;:,-mqj

ARC LIGHT MISSIOXS

(U) On ARC LIGHT missions, PURPLE DRAGON found several l ikely sources of enemy

foreknowledge and forewarning. Under International Civil Aviation Organization

agreements, every t ime an aircraft is scheduled to pass from the control of one air traffic

control (ATC) center to another, it is required to file a flight plan with its local ATC center

and to notify t he new ATC center of its expected arrival t ime and location in that center's

zone of control and request an altitude reservation (ALTREV) for its flight path through

that zone. The new ATC center will then publish a Notice to Airmen ( N O T A ~ l ) , giving

flight particulars such as altitude, flight path, and entry and exit t imes and locations from

the ATC zone, which it broadcasts to al l adjacent ATCs so they will be aware of th e

aircraft's presence.

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( ' f ~ C ) Following the implementation of PURPLE DRAGON'S recommendations on ARC

LIGHT, enemy alerting of 8-52 strikes dropped significantly, at least by the two broadcast

stations identified by NSA. During December 1966, the f irst month of the PURPLE DRAGON

survey, the two NVA s ta tions had alerted 34 percent of ARC LIGHT missions with an

average warning time of e ight and a half hours. In April 1967, a t th e end of PURPLE

DRAGON, NVA alert broadcasts had fallen to only five percent of B ~ 5 2 s tr ikes , with an

average alert time of less than thirty minutes.P' (b ) (1 )

OGADIA

ROLLING THUNDER

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l:.S. Air Force F-105 fighter bombers en route to North Vietnam on a ROLLING THC'.'i"DER mission

U.S. Navy A-4 f ighter bombers on a ROLUNG THUNDER mission

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(U) Because of the radar surveillance problem, PURPLE DRAGON decided to make no

major recommendations, beyond those already mentioned, for eliminating possible sourcesof enemy foreknowledge and forewarning of ROLLING THUNDER missions. Consideration

was given to recommending changes in refueling aircraft communications procedures, bu t

it was decided that the changes would only needlessly complicate refueling operations

without significantly lessening the enemy's warning time.68

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Notes

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(b ) ( 3 ) -P .L . 86-36

1. (U) John S. Bowman, General Editor. TheW-OrldAlmanac of the Vietnam War. (New York: World Almanac,

1985), 104-105;1 IrheGreat Conversation: TIu! Origins and Development of the National

Operations Security Program. (Interagency OPSEC Support Staff, 1991),2,

2. (U) Bowman, 118.

3. (U) Walter G. Deeley. "A Fresh Look at Purple Dragon." SIGNAL, Volume 38, Number 8, Apri11984, 18.

4. Donzel E. Betts, et al. Deadly Transmissions: COMSEC Monitoring and Analysis. (National Security

Agency, CryptologicHistory Series, December 1970), 87 (S NF).

5 . ~ B e t t s , e t a l . , 89-90 (SNF).

. '

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( b) ( 1)

(b ) (3) -50 USC

403

( b) ( 3) -P .L .

86-36

DIA

) ' (b ) (1 )

OGA

6 . lftHistory of a Dragon." DRAGON SEEDS, Volume 2 N ~ ber III, September 1973,29 (TSC).

National SecurIty Agency, Memorandum for the Chief, ADSpJ JSubject: OPSEC Support. 16 June

1971 (TS NF LIMDlS CeO).

7. (U ) Central Intelligence Agency Intelligence/Memoranduml j r h e E f f ~ ~ t i v e n e s s of theROLLING THUNDERProgram in North Vietnam: 1 January-30 September 1966. November 1966,7-8 8 (TSC) E.

Leigh Sawyer. "Pursuit of thelt

CRYPTOLOG, Volume IV, Number 3, March 1979, 1 (TSC).I ~ e l e p h o n e l n t e r v i e w with the Author. 2 March 1992.

8. Sawyer, 1-2(TSC)

9. ~ I b i d . (TSC).

10 Af8CT Ibid ·1 I j n ~ e r y j e w .

1 1 ~ ) Sawyer, 4-5 (TSC)c:=Jnterview(TSC).

12. \TS€f Peeley,18; Donzell E. Betts, et. al.

Working Against the Tide (COMSEC Monitoring an d Analysis). (National Security Agency Cryptologic History

Series,June 1970),131.

13.1'TS6iI I-Director, NSA (DIRNSA) Memorandum toNSA;Rllpresentative,

Pacific Command (NSAPACl. 9 August 1966. <S-CCO); NSAPAGMemorandum to DIRNSA. "VeWarning of

ARC LIGHT Strikes." 29 September 196&(SC):

14. -«'fse lGl"I Sawyer, 4-5 aSC); 1-----......--------11 ~ ! 9 ( T S C J ; Betts. Deadly

Transmissions, 91 (SNFI.

15. NSA InterviewJ 12& February 1 ~ 9 2 , bj . IOH.10.92'Se l l t e r fo f

Cryptologic History ( S . C ~ O l ; Dee ley.T?'; NSAlnterview, David G. Boak, 5 MarchJ992, b ~ I - " , , " " , , ; " " ......__..... .----'and CharlesW. Baker. OH.12-92. Center for CryptologtcHistory (S-CCOl.

:: : f l : : ' ~ : . ' . V . ' . i . ~ : ~ = l l : : : : ~ ~ ~ ~ : ; : : : ~ ~ ; l } ~ ~ . ..•.;~ . H1. 92fS CCOI; 0.;•I.:.e\i: .. .

17lSI

1 8 . ;U i n t e r v i ew . OH-10-92 (S-CCO); Deeley, 17(U). ". ". .//'

19. (U ) Deeley,17 (S) . ;. ". ". .: .-

interview. O H ~ 1 0 - 9 2 ; Deeley, 1 7 - 1 ~ ; B o a k Interview. OH-12-92 (S-CCo>,

interview, OH-10c92 (S-CCQ); Deeley, 17-18; Boak interview. OH-12-92.rS·CCOl.

interview.OH-10-g2($·CCOl; Dee l e y , 18 (S l . \ /

r-"";; ';; ';" '=I-_. . .i;;;;.n;.;.te.,rvieJl,0H-10-92 (S-CCOl; Deeley, 18; BoakirtfepJiew. OH-l2-92 (S-ccol.....__ ...... _

Betts. Deadly Transmissions, 91 (S NF). .1.. . - ..1

2 4 . ~ Ibid., 91 (SNFl.

2 5 . ~ I b i d .

... . / /\\

Belts,DeadlyTransmissions,9"l\S NF).

30. Qterview.OHclO.,g2tS-CCOl; Deeley, 18.

31. " T l ~ ~ ~ L " " ' ' ' ' ' ' ' ' ' " " " " , ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' " " ' T " " " " , . " . , . " . " , . . . , . . " " " " " , = ....., J 6 : = ~ J ; . t e r v i e w . OH,10cg2 (S:OCO); Betts. DeadlyTransmissions. SeN-F) .. . . . . .

( b) (3

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CIA

(b ) ( 3 ) -P .L . 86-36

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32



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/ i ( b ) ( 3 ) -P .L . 86-3

51:

52;

53..

54.

55: (TSE]

5 6 . \ ~ F - - - - - - - " " " " " " 1 (S NF) Betts. DeadlyTransmissions,94 (S NF).

57. Ibid.,.94 (S NF).

sa, ' ¢ )c : J (n te rv iew. OH-I0-92 (S-CC(». .

5 9 . ~ I Betts. Deadly Transmissions, 94 (S NFl ; Deeley, 18 (SCl.

6 0 . ~ D I A TS-SI-60IPL. figure 1.(TSq NFl; ibid. , 11. (TSC NF).

::=t _

32. Ic = J n t e r v i e w · Q t I ~ 1 0 - 9 2 ( S - C C O ) ; Betts. Deadly Transmissions,92 (S NF) . / ' - - . . . . l

33. ID r n t e r v i e w : o H ; T O ; 9 Z ( S ~ C C b ) .3 4 . ~ JI fhe G r e a t ~ ~ ~ v e T s a t i 6 n , 5 ( S ) ;~ ~ t ~ ) 1 ~ ~ ~ ~ ~ n d e r . i n . C h i e f , Pacific, [ n s t r u c t i O n ( ~ I ~ ~ ~ A C I N S T ) 0 0 3 1 0 0 . ~ . O p e m t w a S $ e c u r i t y(OPSEC). 26iHi: ¢)CINCPAC SSO Serial 00026-71.0verationsSecurity (OPSECYReport. 1 JUQe>19'7173-74 (TSC)

37.P) CINCPACINST003100.54 (S); CIJ'(CPAC S S 0 9 0 0 2 6 ~ 7 1 , 7 3 - 7 4 , 76 (TSC).38 .ADi r t f e I " \ ' i ew .OH-I0-92 (S-CCOl.

39 . .¢)CINCPACINST003100.5,1 (S)

40. Jt) Ibid. , 1 (S); CINCPA.CSSb()O.?26.·,11,77 (TSC); .•I'-- '--_,;.....Itnterviewwith the author. 12February 1992\S).

41. ~ CINCPACIl'[ST003 100,5,1-2, 5-6.

4 2 . ~ D i l 1 t e r v i e v , ' , O h ~ 1 0 - 9 2 (S ccoa CINCPACINST 003100.5, 6-7/\8l.

4 3 . ~ n t e r v i e w . OH-I0-92 (8-CCO). (Ui· / / ~ 6 MayJ993 memorandum td - - - ,

I I(U) Joint Chiefs of Staffpublication 3.54. Joint Doctrine for Operations Security, 22 August 1991.

44. ~ C I N C P A C SSO 00026-71, 77 (TSC).

45. ,¢)CINCPAC SSO 00026-71, 74, 77 rrsc» Din t e r v i ew . OH-I0-92 ($-CCOl.

4 9 _ ~ I47. interview. OH-1O-92 .sccoir tnterview (S-CCO);

e au t or. 4 February 1992, / (S NFc:::::readly Transmissions, 92 (S NFl;

Dee ey, 18(_T...;..;;-.;... ___

4 8 . ~ I<S...;;C..;;C..;;iO;';)L,..._-Jinterview. OH-I0-92 (S.CCO)I Interview

( ~ : C C O l ; Boak interview. OH-12-92 (S-CCO); nterview. B'etts,DeadlY Transmissions, 93 (S NF).

49. ~ c : : : : : I n t e r v i e w .5 0 : ~ ) B e t t s ' / D f f l d l ' y ' T r p . . o . ~ ~ I i l l l ~ ~ . J . > 2 . . . I : : U : l . . . . . . . . L ~ .......---1interview. OH-IO-92 (S-CCO)

interview. OH-12-92(S'CCO);

DIA

(b ) ( 3 ) -P .L . 86-36

33 TOP SECRET UMBR>\



l'6J1 seCRET tlMBR-A

Part III

PURPLE DRAGON at War

COMMANDER IN CHIEF PACIFIC

CINCPAC PURPLE DRAGON report coversheet ( a r t w o r k ~ ~ L . . . . - ---IIUSN)

P,ST R 8 L 8 A S l \ ~ L P ; f O P"REIGN NAIIONAtS

35(b) ( 3 ) -P .L . 86-36

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OPSEC INACTION

I I

"--- .....,.,b) (1

CD) The teams also produced some fourteen OPSEC reports. Each PURPLE DRAGON 0

report consisted of the results of surveys conducted during the reporting period as well as

regular updates on the OPSEC status of Operations ARC LIGHT, BLUE SPRINGS, and ROLLING

THUNDER. Following the termination of ROLLING THUNDER in the spr ing of 1968, PURPLE

DRAGON began including regular updates on th e Strategic Air Command's SR-71 D

reconnaissance program over Vietnam and the Korean peninsula, Operation GIANT SCALE.

PURPLE DRAGON reports were unusual in that they did not go through the usual staffing

process at CINCPAC bu t were issued directly as written by the OPSEC branch. 1

CD) Following ar e a few of th e more significant operations security surveys conducted

during th e Vietnam conflict, which are representative of peRPLEDRAGON's usual activibes

and findings.

U.S. NAVYIMARINE CORPS AMPHIBIOUS OPERATIONS

TO.. 5eERET UMBRA 36



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U.S. Marine amphibious landing, South Vietnam

NOT RKlsi: 'S/tHee 'f a Fetit6-l. NAtIONALS

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SOUTH VIETNAM

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Operation BOLD MARINER,Batangan peninsula and Mo Due, South Vietnam

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u.s. 9th Infantry soldier in the Mekong delta

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C.S. ground forces receiving tactical air support in South Vietnam

!\e'F I t E L E M ! 7 \ ~ L I ' : 'Fe FOltEI8li !41<'Fle!4l<L8

TOP SECRET U M ~ f t A 48



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49

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. 'FOP SEERE'F l:JM8RA

(C ) Following the PURPLE DRAGON surveys of Mobile Riverine operations and Army

ground operations, as with mos t PURPLE DRAGON surveys dur ing V ie tnam, t he OPSEC

posture of the surveyed organizations improved, at least temporarily. More important,

however, evidence of enemy prior awareness of the operations significantly decreased as

the surveyed units implemented suggested changes in procedures. U.S. intercept of enemy

alert messages dropped off, and contact with the enemy usually increased. These positive

results, however, were almost invariably only temporary. In most cases, the enemy, being

denied one valuable source of foreknowledge of U.S. intentions and capabilities by the

improved operations security ofthe units involved, would cast about unt il they had found a

new source of information to take its place. Then, evidence of the enemy's prior knowledge

would again surface and the OPSEC procedure would begin again.

ARC LIGHT OPERATIONSREVISITED

D

TOP SECR.H l:JMBAA 50



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(b ) (1)

OGA

p.-" .... , ~ __:::.._-_._._..•.._,._ .•._...::,..

u.s. ground forces, fo reg round, watch th e resu l ts o f a B-52 strike in South Vietnam

dOT r t ~ L r : A ~ A r s L E Ie F c ! t ~ I e N NAtIONALS

DIA

51 I UP ~ ~ ( K ~ T UMBRA



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53

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Notes

(b ) ( 3 ) -P .L . 86-36

2.

TheGreat Conversation..4-5.r . - - - - - - ')Bowman, 428; CINCPAC SSO-00021-68, Operations SecurityReport. 1Apri11968, 18, 21 (TSC).

3. ~ I b i d . , 18 (TSC).

4. ~ I TS-SI-60IPL, 15 (TSC NF),

5. ~ C I N C P A C SSO-0002I-68, 18 (TSC).

6. ,Cll81Ibid.,18-19 (TSC); DIA TS-SI-60IPL, 15{TSCNF).

7. ~ C I N C P A C SSO-00021-68, 18-21 (TSC); orA TS-SI-60IPL, 15 (TSC NF).

8. CINCPAC SSO-00021-68, 18-19 (TSC); DIA TS-SI-60IPL, 15 (TSC NF).

9. ¢CINCPAC SSO-00021-68,19-21 (TSC).

10. Ibid., 18-19 (TSC).

11. Ibid., 19-20 (TSC).

12. !J:8'l Ibid., 21 (TSC);c::::::=Jnterview.OH-I0-92 (S-CCOl.

(b) (1)

OGA

DIA13. CINCPAC SSO-00021-68, 19-21 (TSCl.

14. ( T s l p i ~ t e r v i e w . OH-I0-92 (SCCOl; Deeley, 19.

15. CINCPAC (SI) SSO-00051-68. CINCPAC Operations Security Report. 1August 1968,38-41 (TSC).

16.;a, CINCPAC SSO-00048-69. Operations Security (OPSEC) Report. 1 April 1969, 1(TSC NFl; Bowman, 219.

17. CINCPAC SSO-00048-69 1-3 rrscNF).

18. Ibid., 4-5 (TSC NF).

19. Ibid., 5-6 (TSC NF).

20. (U) Bowman, 219.

21. (U) William B. Fulton. Vietnam Studies: Riverine Operations 1966-1969. (Washington, D.C.: Department of

the Army, 1973),24- 25.

22. (U ) Ibid., 26-27,42,58-59.

23...Q!B1CINCPAC SSO 00051·68, 19 (TSC).

24..fP6Hbid., 19-20 (TSC).

25. Ibid., 20 (TSC).

2 6 . ~ I b i d . , 20 (TSC); Fulton, 65-66.

2 7 . ~ CINCPAC SSO 00051-68, 21-22 (TSC).

28."'ffStIbid., 23 (TSC).

29. ~ I b i d . , 22-23 (TSC).

30. i'ffltIbid., 23-26 (TSC).

31. ~ I b i d . , 26-27,30 (TSC).

32. ~ I b i d . , 27-28 (TSC).

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33. 't"fSUbid., 28 (TSC).

34. ~ I b i d . , 28-29 (TSC).

35."'T'FSU::INCPACSSO-00021-68, 1-2 (T8C).

36. ~ b i d . , 22 (T8);I ...l

37. 't'r$Jbid.,15, 20 (T8C NF); CINCPAC 880-00021-68, 22 (T8Cl.

38.l:'rsubid., 22-23 (T8C_). ...,

39. ~ b i d . , 22 (TSCl;I ---1

40. ~ I N C P A C SSO-00021-68, 22, 24 (T8C).

41. ~ b i d . , 23-24 (TSC).

42. ~ I b i d . , 23 (TSCl;Ir-----------

43. {T$.CINCPAC SSO-00021-68, 23 (TSC).

44. ~ I N C P A C SSO 00064-70.Operations Security(OPSEC) Report. 1 December 1970,72 (T8C NF).

45. ~ b i d . , Appendix I, 1 (TSC NFl.

46. ~ I b i d . , Appendix I, 37 (TSCNFl.

47. ~ b i d . , Appendix I, 38 (TSCNF).

48. ~ b i d . , Appendix I, 38-39 (TSC NF).

49. 'l'sl.Ibid., Appendix 1,39 (TSC NFl.

50. ~ I b i d . , Appendix I,41-42, 43 (TSC NFl.

51. ~ I b i d . , Appendix I, 44-46 <TSC NF).

52. ~ B o a k interview. OH-12-92 (S-CCOl.

. (b)

OGA

W5'f KI'::LI'::A;'ABLI':: '1'6 fo'6KI'::f(':}!( K A ' f I 6 t ( A L ~

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Ib ) (1 )

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13 0

Ib ) (3 ) -1 8 USC

798

Ib ) (3 ) -P .L .

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Part IV

NSA and PURPLEDRAGON

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403

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D

~ B e s i d e s providing/COMSEC expertise to the OPSEC branch in the Pacific, NSA

also se t about to provide dedicated SIGINT support to PURPLE DRAGON. Beginning in April

1967, NSA drafted Technical Instructions ('rECHINS) for Agency and SCA elements, both

at Fort Meade and in the Pacific, that established procedures for handling and reporting

SIGINT evidence o FCINVAJoreknOwledgeand forewarning of U.S. operations in

the Pacific.

('f80 ~ T V ) . . T h e s e TECHINS requiredall UiS. SIGINT field stations to

continuously scan their daily intercepted'unaterial for any /indications of Asian Communist

awareness ofU.S. and Allied reconnaissance/strike.-related flight. Indications ofsuch awareness

will be checked against station records for correlationwith known mission schedules. Indications

ofAsian Communist awareness of reconnaissance/strike-related activitywill be reported in the

appropriate vehicle. . . .3

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","

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403

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798

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!,Ib) (1 )

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5j ' Ib) (3 ) -P .L .! 86-36

( ' f ~ C NF) The TECHINS also established reporting vehicles for the enemy awarlirj.e:;s

reports, ranging from tactical reports at fla.sh precedence for intercepts which could beclosely correlated with imminent Allted operations and could be released dir.ectlytd t h units involved, to weekly and monthly Asian/Communist (later Pacific Area) Awareness

Reports, which summarized al l SIGINt evidence of enemy foreknowledge or forewarningduring t h precedin.g p : r i o ~ . 4 Over time, the TECHINS would be expanded in scope,• f i ~ s t .•.to cover mtercept indica ti ng I '" ' ' '...\ i •• •pr ion

awareness of U.S. and Allied operations and communications i n d i c a t i ~ g such awareness,

and, second, to cover all U.S. and Allied/combat ope rationa.vrather than just

reconnaissance and strike-related flights."

~ A l o n g with the new reporfiing' instructions on enemy foreknowledge and

forewarning, DIRNSA decided to replace the 'ad hoc nature of support to PURPLE DRAGON

with a more permanent mechanism to coordtnatc\the.Agency'sOPSEc-related activities

with the CINCPAC OPSEC branch. General Garter, therefore/in June 1961 established

within NSA's Office of Asian Communist Nations, thendesig'nated B Group, a B Group

Joint Task Force (BJTF) to provide dedicated SWINT support/to the OPSEC program in the

Pacific." The mission of the BJTF was "to review the SIGINT,hidences offorewarning from

all available sources, in order to deterrhine lnoton ly whafthe enemy may be exploiting,

but also how he is doing it."? A major focus of theBJTF's.Analysis of enemy awareness was

to determine whether any U.S. codes or ciphers wEtre beiilg exploited."

a ee\'), Among th e Agency organizations included in th e BJTF were

representatives of the Agency's Cornmunicaticns' Security /Division,Sl ,as well as

representatives of the various B Group branches directly involved in the Agency's efforts

aga inst the North Vietnamese, VietCong, . . targets. These

included B21, the office which had first repor ted the alerts of ROLLING

THUNDER missions. for the vastmajority of ROLLING THUNDER strikes througbBut the ini tial pt;RPLE/.DRAGON survey, and,

in fact, continued to issue them regularly light through to the termination of ROLLING

THUNDER in April 1968.1 • ../ . . /\ // // 1

for more than a year after ROLLING TH{,JNGER ended, but B21 concludedvthat most of these

later alerts were merely training e x e r c i ~ J s for the CFNVN.9

r-- ......... .......----------.. . , . ,i.:. .O-i-V-is-i-o-n-o.Jf· t ~ ~ \ ~ ; f i : : g : : { i a A ~ \ i ; I ' - - - - - - - - - . , ?45, was made the focal point for the/BJTF. B45 had

i-=''''''''''''':..;.;.o .......=''"'''''''''''lS''''c'''''o""'v''''''ery of \ //Iorganization

communications net! • ~ h a t was apparently reporting Qn/U.S. Navy,

Marine, and Air Force operations in the Gulfof Tonkin and northern South Vietnam. The

ne t consisted of a cont ro l statio and two o u t s t a t i o n ~The network was first noted active i n

....._-------------_ ....

(b)(

(b)(

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rep SECRET UMBftA

___________ ~ . , . . . . . . . . , . . T " " " " " ' : " " " ' l I A third outstation in the netl ...... ---'

IWas also identified, bu t it was seldom active.10

ONI(b ) (1 )

U.S. forces tactical data, so cal led "blue force data," to a id them in their analysisef a

hostile SIGINT target.

-a'SCT Throu hout the Vietnam conflict the Nav maintained an avera e of(b ) (1 )

analysts learned from t e data that every day at 0700 hours local, these carriers

would transmit their locations to CINCPAC headquarters in Pearl Harbor. They further

noticed that I

1 -------)T9:f R ~ b ~ l z S l t B b 8 :f a FaR818N NA'fI6HJ!!l:LS

59 Tap SECRET b1MIlRA



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(b ) (1 )

OGA

'-- ----IONI -5

(TSC) What they r ead surprised them. Thel Icommunications net?

d e s i g ~ a f e d l Iturned ou t to consist of reports of primarily U.S. ) i a vy and Marine

aircraft activities off the carriers in the Gulf. Some transmissions consisted of direct

transcriptions of U.S. aircraft communications traffic, no more and no less.

Bu t the element of the

He'F RELEASABLE 'Fe FeREIt'Ecf11' .J!<'FI8!\ALS

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communications that most surprised the NSA analysts reading them, was that everything

86,,-36 transmitted on th , ret , except operator chatter, was in English. 12

i 1 ' ~ c r w h y l Iwas in English no one could say. One plausible suggestion was

IOr perhaps they were just too' - b " ' u ~ s - y -<.-to-. - t r - a - n - s - l a - t " ' e - t - h " ' e " ' m - · ~ a - s - s - o - r - m - a - t - e - r - i a - l - - - a f - t - e - r - a - l l - , - a - t - i - t s - p - e - a.....k rlone was sending

over 2501 . Imessages a day t4 I~ M o s t of t h Iintercept observed in ! ~ e f l e c t e d activity by the

U.S. aircraft'carriers in support of ROLLING THUNDER missions and other operations, bu t

there were /also reflections of V.S. Air Force KCQ35 tanker aircraft, reconnaissance

aircraft, and B - 5 2 ~ o n ARC LIGHT missions. While most U.S. communications reflected in

I Iwere in plain tex t, B45 was able to/show that at least some U.S. operational

codesmay have been compromised, either through traffic analysis or cryptanalytic attack,

and were regularly being exploitedI .. IWhatever the m e t h o d s l ~ ~ __ ~ - : - - - - - JI lused to read the U.S. traffic, B45showed they were regularly able to intercept the

iU.S. signals and retransmit the content of t h e ~ Ion average within

five minutes/l"

~ c r r h ~ Inet continued to provide valuable intelligence to the U.S., and

important/indicatipns 04 Iforeknowledge of U.S. operations in Southeast Asia, until

late' 1970, when the. circuit suddenly/and for no apparent reason went dead. A debate

ensued as to whetherornol I----..f!P8C)"'"Other reasons for the loss of t h Isignals were also presented: the

~ a trouble getting the sys tem to function properly, and it was

......,.,p-o...s..,i'l"'b"l'"le-:"':"'thr-·...y-s...m-p"l"ly....gave up on it as being too complicated t o o p e I " a t e ~ fay

also have abandonedI . b t b ~ b e t ~ e c a u s e they had developed a bettersys tem. The c ircu it was qUickly replacedpy a parallel net using a different encryption

system.

(b ) (1 )

( b ) ( 3 ) -50 USC 403

(b ) (3 ) -18 USC 798

(b ) ( 3 ) - P . L . 86 -36

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.•..•____ ~ ~ = - ' = " " " " - - : ' - - - ' I The new system remained active for approximately a year before it

too went off the air, probably to be replaced by landline.

'1TS6+-With th e loss of thel ~ 4 turned it s a t t e ~ t i o n s to other,

less valuable targets until th e end of u.s. involvement in Southeast Asia, when the

_______Idivisionwas disbanded and the target went into a caretaker status."

Whilevthe analysis and reporting of t h pet was it s major

responsibility, B45 supported th e CINCPAC OPSEC program in other ways as well. As

focal point for th e BJTF , 845 was responsible for producing weekly and monthly

summaries of al l SIGINT reflections of enemy foreknowledge and fo rewa rn ing o f U.S.

military operations.xfsecause of th e quantity of such material, this requirement was later

reduced to only weekly summaries. The BJTF was also responsible for gathering both

SIGINT and collateral (!vidence of foreknowledge of U.S. opera tions, not only by .1 _

Land even

from 1 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = == = = = = = = = = nd forcoordinating all NSA OPSEC-related repor ts . The BJTF produced reports and briefings onit s findings for PURPLE DRAGON\team members and the U.S. military andi#telligence

communities, as well as orientation tours for personnel being assigned to the/OpSEC team

atCINCPAC. 15

(8 eeOr-As SIGINT often provided the evidence of OPSEC weaknesses, it also served as a

major indicator of OPSEC successes. Throughout the war , one of the most-common reasons

for performing an OPSEC survey of a, particular operation was SIGINTeividence that the

enemy had foreknowledge of it. In ongoing operations, such as ai r operations, the SIGINT

evidence often took the form of alert messages prior to individual missions. When PURPLE

had finished d i dati dRAGON a 1n1S e survevmz an oueration an it s recornmen ations/were irnpl emente ,

the OPSEC team would o f t e ~

'(sJI

)b)"GA

DIA

\\./</

b) (1 )

( b ) ( 3 ) - 50 USC 40 3

(b ) (3) -18 USC 79 8

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62

....



eeorrs the f inal analysis, NSA support to PURPLE DRAGON was an important,

perhaps vital element in the success of the OPSEC program in Southeast Asia. As one

employee ofB45 put it , PURPLE DRAGON "wouldn't have happened without NSA." 17

(s CeO) But NSA's support was also a success story within the Agency itself. Just as

PURPLE DRAGON was originally conceived as a multidisciplinary organization, so too was

the Agency's support multidisciplinary. In support of the OPSEC effort in PACOM, Agency

personnel from al l of the cryptologic disciplines - cryptanalysts, traffic analysts, signals

analysts, linguists, reporters, COMSEC specialists, and intercept operators - both military

and civil ian, from a variety of offices with a variety of targets, at Fort Meade and at field

stations throughout the Pacific and around the world, worked together closely to improve

the combat effectiveness and save the l ives of U.S. and Allied servicemen and women in

the rice paddies and the jungles, at sea, and in the ai r throughout SoutheastAsia."

Notes

(b ) (1 )

OGA DIA

o f ' ~

(1 )

USC 40 3

) (3) -18 USC 79 8

(3 ) -P . L . 86-36

1 I2. ke1ephone Interview with the Author. March 1992 (S-CCOl.

3 . NSA Technical Instructions ( T E C H I ~ S ) Number 4065. Report o f P O S S i b l ~ r - - - - - - - - ~ 4 w a r e n e s sofFriendly Reconnaissance and Strike-related Missions (TSC). 3 April 1967, 1tTSC l.

4. Ibid., 1-3 (TSC).

5. (Tlii lHF CCO) Memorandum for the Chief, ADSP, Mr. Oliver. Subject: OPSEC Support. 16 June 1971 <TS NF

LIMDISCCOl.6 . 131 (TSC); DIATS-SI-60IPL,47ITSCC'<n

7. ~ I b i d . , 47 (TSC NFl.

8. ~ i b i d . , 48 (TSC NFl.

9. CeCJi1-rSA I n t e r v i e ~ r - - - - - " " " " ' - - - l March 1992, witH PH-1l-92. Center For

Cryptologic History (S·CCO); ClNCPAC SSO-0001\-68, 14-15 (TSC) t lNcPAC SSO 00048-69,27 <TSC).

10.fS eeett knterview. OH-1l-92 (S-CCO); 3 / 0 0 / 2 4 5 9 6 J 0 2 1 AUG 73; 2/0c=JR04-70, 30

April 1970; 2/0c:::Ji0'j 'c67, 152130.Z NOV 67,

~ ~ ~ ~ / / fnterviBw.OH-11-92(S-CS3l; ~ t q / / ~ 0 9 - 6 7 ' 2 8 A U G U S T 1967; 2/0c::JR04-70,30

1 2 : ~ ~ n t e r v i e w . OH-1J,91<S-CCQ);N"SASerial 3 3 . 0 5 ~ . R a d i o S i g n a l Notation (RASIN) Manual.J u n e l ~ 8 , 51 ( S C ) ; 2 J O I < I R { W 7 0 3 o , ~ P B - I L 1 9 7 0 ; ? / c e : : : F 0 9 - 6 7 , 28 AUGUST 1967.

~ ; ; ~ ; . ~ 3 ~ i ~ 1 ~ g B ~ : ~ ; G I 7 c p A ~ SSO 00064 70,73 iTSC NFl; VeDa04 70,301 ~ , ~ ' P ~ . c 3 / 0 0 1 2 4 5 9 6 , 7 3 c : : : : : : : J 2 1 e - l J G 7 3 . d .. .... Fnterview. OH-11-92 ( S - C C ? ) ; I ~ ~ ; - - ~ _i t l t ~ r ~ i ~ " " ; R 6 b e r t E . N e w t o n : 7 ' h e C a p t l l r e o f t h e U S S P u e b I o a t l d t$Effecton SWINT Operations. (1992, CenterforCryptolcgfc I:Iis.t(}ryl;144-145.

1 5 l i n t e r v i e W . Q l i : l l : 9 2 ( S ~ ~ ~ ? 1 t n ~ ~ m .":,?:

(b ) ( 3 ) -P .L . 86-36

63 lOP §[ERET tJMSRJ\



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16. ts=eeef tnterview. OH-11-92 (S-CCO>.

17.4 eeerIbid. (S-CCQJ.

1 8 . ' " t t t - e e ~ Ibid. (S-CCO).

(b ) ( 3 ) -P .L . 86-36

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,.

(b ) ( 1)

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IUPSECRE r tJM81\A

VCINVA INTELLIGENCE STRUCTURE

- ' T ~ eeen- At the top of the VCINVA intelligence structure was North Vietnam's

Central Research Directorate (CRD) in Hanoi. The CRD, sometimes described as "Hanoi's

DIA," had responsibility for strategic, national-level intelligence." Below the CRD, the

Central Office, South Vietnam (COSVN), analyzed and disseminated tactical intelligence

to VCINVA forces throughout the RVN and served as a point of contact between the CRD

and uni ts in the field. 7 Finally, scattered throughout the RVN were VC/NVA tactical

units and indiv idual agents. They could either pass their information up to COSVN for

analysis or, in some units, analyze and use it for tactical advantage thernselves.f

~ O all sources of information, the VC/NVA valued communications intelligence

most heavily, with enemy PWs and ralliers describing it variously as "the easiest, safest,

and fastest" means of obtaining intelligence, and as a "continuous source of information"

on All ied plans and operations." All level s of the VCINVA intelligence system were

involved in the collection, processing, analysis, and production of COMINT. The CRD in

Hanoi, for example, attempted the cryptanalysis of medium- and high-level U.S.

cryptosystems. While there is no evidence the Nor th Vie tnamese had any success

cryptanalyzing high-grade U.S. systems, the CRD was successful against some lower

grade codes and ciphers, such as one used to transmit airborne radio direction finding

results in the RVN. 10

( ~ T F ) Much of what is known about VC/NVA COMINT activities in the RVN comes

from documents and personnel captured during Operation TOUCHDOWN in 1969. During

TOUCHDOWN, soldiers of the 1s t U.S. Infantry Division in Binh Duong Province near

Saigon managed to capture twelve of the eighteen enemy personnel assigned to a local

Technical Reconnaissance Unit (TRU), a VCINVA tactical COMINT uni t, a long with i tems

of equipment and some 2,000 documents."

~ B a s e d on th e review of TOUCHDOWN-related materials, as well as

interrogations of enemy PW sand ralliers, it was clear that the enemy maintained an

extensive and efficient COMINT network in th e RVN. COSVN, through i ts Military

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Intelligence Bureau (MIB), oversaw the activities of at least 4,000 enemy personnel in the

RVN estimated by CINCPAC to be engaged in the inte rcept and ana ly sis of Allied

communications in 1969. The actual number may have been as high as. 5,000 personnel.

The extent of the enemy COMINT effort inside South Vietnam was particularly shocking, as

the best previous estimates of the enemy's COMINT effort had suggested that no more than

300 enemy personnel were engaged in COMINT activities inside South Vietnam.V Enemy

TRUs were apparently established in every part of the RVN and ranged in size from 406

personnel in t he 47th Technical Reconnaissance Battalion colocated with COSVN along

th e Vietnamese-Cambodian borde r in early 1967, to individuals performing signals

intercept operations alone in Saigon."

OPERATIONSOF THE TRUs

;er ' l 'he TRUs used a combination of captured and stolen U.S. radio equipment, as well

as commercial equipment from Japan and Western Europe, and radios supplied by the

Communist Bloc countries to conduct intercept. They also used small, battery-operated

tape recorders to aid them in exploiting non-Vietnamese voice communications. 14

DRV signals intercept officer at work

MOT j;{i2bi2 \g '\8'"'8 ' fO FOREI8!1 N J l c ' f I 5 N ' i i L ~

67 TOP SECRET UMBKA



Tell SeeIU!T UI\1I8RA

of enemy intelligence during t he war in Southeast Asia. The VCfNVA also maintained an

extensive espionage program in the RVN and perhaps elsewhere in the Pacific. Individual

agents working in the RVN were controlled by Military Intelligence Sections (MIS), which

were directed by the Strategic Intelligence Section (SIS). The SIS reported directly to the

MIB at COSVN, where agent information was ana lyzed and either disseminated to

military units in the field or passed on to the CRD in Hanoi ;" There was also evidence that

VC/NVA tactical units recruited their own agents to provide them with local, tailored

intelligence.

""'(C}The VCfNVA were able to infiltrate agents into al l levels of RVN society, from

high- rank ing mil itary and civilian personnel in Saigon to peasant children in the

countryside. The enemy also attempted and, often it seemed, succeeded in placing agents

among the Allied forces, especially the Americans, usual ly as workers in local military

ins tallat ions . The enemy typically sought communist or DRV sympathizers to recruit as

agents but were not unwilling to resort to threats and violence to coerce people into spying

for thern.:"

~ I n t e r r o g a t i o n of enemy PWs and ralliers gave general indications of VC/NVA

espionage in the RVN. Fo r instance, sympathetic civilian authorities often provided the

VC with information on Allied troop concentrations in their areas, while local villagers

would provide t hem with local hearsay on Allied intentions.:" Villagers were a lso

responsible for warning the VC of Allied ac tivi ti es . These v il lagers would use "such

methods as ringing a gong, shaking a rattle, firing shots into the air, blowing a whistle,

beating a bamboo stick, blowing a horn, setting a fire, or igniting smoke grenades" to warn

the enemy of Allied t roop movements. The VC/NVA also would force interpreters and

translators working for U.S. mili tary and civilian agencies in the RVN to steal documents

and provide information from their jobs."

-t€'r1'he enemy also made a concerted, and successful, effort to infiltrate ARVN units inorder to provide more timely and accurate information on proposed ARVN operations.

Often, draft-age VC personnel would allow themselves to be arrested as draft evaders, and

would then volunteer for duty in target areas. VC/NVA personnel even gained access to

ARVN-controlled installations by wearing captured or stolen RVN armed forces uniforms

and passing themselves off as South Vietnamese military personnel. 33

~ ?fFt When the enemy was not able to place an agent inside a particular Allied

installation, they settled for placing one near the installation or in those places that Allied

personnel were known to frequent off the job, and relied on observation and eavesdropping

to gather information. The enemy recrui ted vendors, truck drivers, carpenters, even bar

girls and prostitutes to serve as agents." The VC was even reported recruiting fourteen- to

sixteen-year-old children to hang around Allied radio-equipped vehicles and copy the

frequency settings on the communications gear, and th ey ar e believed to have placed

NOT REI §; A A ~ b 'FQFQFUH6N N k ' T ' 1 6 r ( 2 \ L ~

~ ' .lOP SECRET l:JMBRA 70



TOil SECRET I,JM8RA

(b ) ( 3 ) -P .L . 86-36

DIA

(b) (1)

OGA

Notes

he Great Conversation, 5 .

2. (

3. CINCPAC Serial SSO 00026-71. Operations Security (OPSEC) Report. 1 June 1971,2 (TSC).

4. ;e(Combined Intelligence Center Vietnam (CICV) Serial MACJ231·6. VCINVA Alert an d Early Warning

System. 30 June 1970, i (C).

5. ~ I b i d . , 1 (C).

6. CINCPAC SSO 00048-69. Operations Security (OPSEC) Report: Extracts from Appendix I, 3 (C);

Lieutenant General Marshall S.Carter, DlRNSA, Memorandum to Director,Central Intelligence Agency, Chief,

JCS, and Director, DlA. Subject: Project RATHSKELLER. 12 January 1968 (TSC).

7. CINCPAC SSO 00048·69. Extracts from Appendix I, B-1 (C); Department of Defense Intelligence

Information Report <DODIIR} Serial TCSR PAC 08-70. Study ofVCINVA Technical Reconllaissance Units, 14

July 1970, 2 <C).

8. ('l:'s..CINCPAC SSO 00048-69. Extracts from AppendixI,B-1 «».

9. ~ C I N C P A C SSO 00048'-69. Extracts from Appendix I, 4 (C); DODIIR Serial 6 028 2422 68. Prior Knowledge

ofAllied/U.S. Operations. 22 June 1968,2,3 (Cl.

10. ~ DlRNSA Memorandum to Director CIA. Chief. .rCS. and Director. DIA.Serial N0040. Subject: Project

RATHSKELLER. 12 January1968(TSC); I \ I11. ~ C h a r l e s W. Baker. "Military Effects of Poor Communications Security (COMSEC) --Some Historical

Examples" (unpublished.manuscript), (1991 , National Security Agency, Center for Cryptologic History), 3,4 (TSC

NFl! ,"Viet Cong SIGINT and U.S. ArmyCOMSEC in Vietnam." CRYPTOLOGIA, Volume

XIII, Number 2, April 1989,144- 145.

12. ~ ) o O D I I R TCSR PAC 08-70, 2 (C); (ClCINCPAC SSO 00048-69. Extracts from Appendix I, 1 (Cl; Boak

interview. OH-12·92 (S-CCO).

I3.-te7CINCPACSSO 00048-69. Extracts from Appendix 1,1, B-2 «»,

14. JKj Ibid., 3 (C); CICV MA-CJ231-6, 2 (C).

15. ~ eOOl DODIIR Serial TCSR PAC 15-69. Study of VCINVA Technical Re.connaissance Units (TRUJ. 18

November 1969,2; 3 (S·cCO); U.S. Army Security Agency (USASA). TAREXReport TCSR 04- 71. VCINVA

COMINT Effort. 8 March 1$71,5,7 (C).

16. (C CGO) USASA TAR.E· XReport TCSR 04-71. .5, 6 (C); DODIIRSerjal TIfR RVN 24-68. Interrogation ofLeVan Ngot, 4 November 1968,3 (C-CCO); DODIIR Serial ' VC Communications in MR2. 14

January 1968,2 (C). 1

1 7 . ~ U S A S A TCSR 04-71. pg.4, 5 (C); CINCPAC SSO 00048-69. Extracts from Appendix I, 3 (C).

18. ¢>Ibid., 2 (C ) ; c= J l45(C) .

19. CINCPAC SSO 00048-69.Extracts from Appendix I. pg.3, 4 (C).

20. (0 600) DODIIR TTIR RVN 24-68, 4, 5 (C-CCO); DODIIR TIR RVN 307-68. VC Operations to Obtain

InformationFromARVN an d Allied Forces. 31 December 1968,4 (C-CCOl;L:]145(C).

21. -t6 cew USASAPAC TCSR 04-71 4, 8 (Cl; DODUR TCSR PAC·15-69. Study of VCINVA Technical

Reconnaissance Units (TRUJ. 18 November 1969, 3, 4 (S-CCO); TAREX Reports. 15 June 1970, 1 (S).

22. ~ C I C V MACJ231·6, 4 (C); DODIlR TCSR PAC 08-70, 5 (C).

lOP 5!(]lET I:lM8RA 72



fOP SECRH I:IMBR*

23. ~ D O D I I R IR 6028013868,2 (C).

24. i s S S ~ D O D I I R TTIRRVN 24-68, 6 (C-CCO); DODIIR TCSR PAC-I5-69,3 (S-CCo>.

2 5 . 1 t r C C ~ DODIIR TTIR RVN 24-68, 4 ( C -CCO )D4 5 .

26.1C-Ce8rDODIIR SerialTIR RVN 308-68. Monitoring ofARVN and Allied Radio by the VC 186th Battalion. 3

December 1968,4,5 (C-CCO).

27. ~ O D I I R T C S R P A C 0 8 - 7 0 , 6 ( C ) .28. (S SSQl DODIIRTTIR RVN 24-68, 5 (C-CCo>.

29. DODIIRTCSR PAC 08-70, 2 (C).

30. f€tCICVMACJ231-6,5 «».

31. DODIIR Serial IR 6 028 2730 68. Prior Warning ofAllied Operations. 11 July 1968,2,3 (C); DODIlR IR

6028013868,3 (C).

32. ~ I V C MACJ231-6,5,6 (C). (b) (3) -P . L. 86-36

33. ~ Ibid., 6 (C).

34. (SG ~ f F l Ibid., 5, 6 (C};Donzel E. Betts. The Front 4 Intelligence Threat Puzzle lDraft Copy). December 1971,

161SC NF).

35.ietUSASAPAC TCSR04-71, 7 (C); CICV MACJ231-6, 3 ( 0

DIA

" (b ) (1)

OGA

36. (SS ~ f F l DODIIR TCSR PAC 08-70, 21C); Betts. The Front 4 Intelligence Threat Puzzle (Draft Copy), 16 (SCNF).

37. J£!)TAREX Reports, 1 IS); DODIIRserial IPriorJ(llOwledge ofAlliedJU.S. Operations. 22 June1968,2 (S).

38. ~ D O D I I R I IDODHRTTIRRVl\i24.SE,6(C}.

3 9 . ~ C C DODIIRTIR RVN 307-68,3 (C-CCO); TAREX Reports,'VSL

40. ¢DODIIRI I41.J2"Ibid., 2. (C); TAREX Reports, 3 (S).

NOT REI EASABI E TO F O R I i : I Q ~ f ~ f A ' F I 8 N A h S

73 TOP SECRET U r o ' l ~ R A



-

PURPLE DRAGON: LESSONS LEARNED

DIA Ib

OG

(U) On 27 January 1973, representatives of the Uni ted States, Nor th Vietnam, South

Vietnam, and the Viet Cong signed "An Agreement Ending the War and Restoring Peace

in Vietnam" in Paris. The agreement called for the withdrawal of the last 23,700 D.S.

troops and advisors left in South Vietnam by the end of March. Although U.S. servicemen

and women would continue to be actively engaged in Southeast Asia for another two years,

the Paris Peace Accords effectively marked the end of the Vietnam War for the United

States.

(D) By the end of the war, PURPLE DRAGON and the U.S. operations security program

were a little over six years old. During that time, what did the U.S. military learn from

PURPLE DRAGON? And how successful was the U.S. OPSEC effort in Southeast Asia?

PH¥Y' RSbl.'h4i:St\BLI3 'f a FaR13I6N Nlc'fI6H'lcLS

..

81 ";OP SeeRE i UMBRA



TO,. seeReT tlM8RA

CU) When U.S. military co mman der s f i rst received proof from t he N a ti on a l S e cu ri ty

Agency t h at th e enemy was forewarned of U.S. operations in Southeast Asia, no one coulds ay w it h certainty how he ha d obtained his information, and, w it h ou t k no w in g t hi s, there

was no wa y to prevent hi m from obtaining more. I t was in order to discover how t he e ne m y

o b tai ned h i s i n fo r mat io n , an d to p re ve n t h im from obtaining more, tha t PURPLE DRAGON

was born.r----------------------------------, (b) (1l o

Tap SECRET tlM8R"A

NVI R E L E A ~ A e L ~ T ~ f 'eftEI6N NA'f'fOUALS

82



TOP 51!eRET l::JMBAA

31. ;.81"CINCPAC SSO 00054-71,188 (TSC NF).

32. iS€) } t CINCPACMessage 7349 to MACV 300136Z JUL 72 (S); JCS Messa e 0020 to DIRNSA 261639Z

JUL 72 (SC); JCS Message 0021 to CINCPAC 261641Z JUL 72 (SC); SA 86 , Memorandum to

Captain Smith, JCSJ34. 23 August 1972 (SC); CINCPAC.Operatio'l8 ecunty eport, T ~ A to Appendix II. 1

December 1972,8 (SC NF).

33. !knCINCPAC. OperationsSecurity Report, Appendix II. 1 Jun!i!1972. pg.I-5 (TSC).

34. ~ S Pacific Representative in Vietnam, Message to DIRNSA. 300702ZAUG 70 (TSC).

35. S12'l St. C. Smith, Chairman,OPSECMonitoring Group,Memorandum (C).

36. }P'l Ibid. (C).

37.;Q1 Ibid. (C).

38. fJ/f) Ibid. (C)c::::::::J.nterview; Deeley, 19.

39. NSA PacificRepresentative in Vietnam Message to DIRNSA. 300702Z AUG 70 (TSC).

40. linterview. OH·11-92 (S-C.cO); St . C. Smith, Chairman, OPSEC Monitoring Group,

Memorandum (C).4 1 . ~ - - - " " ' - " " " ' - - - - - - '

(b) (1)

OGADIA

(b ) ( 3 ) -P .L . 86-36

NOT Rf'! EASAB! E TO EQRE!c.N NATWNAI S

87



,

-"

..

Part VII

PURPLE DRAGON at Peace

OPSEC AFTER PURPLE DRAGON

~

m,. SECRET l:JMBRA

\(b) (1 )

OGA

DIA

CD) Therefore, it should not be surprising that the surveys conducted by these OPSEC

branches often showed a lack of understanding of the purpose of operations security. In

wo:r RIkJ"i:' $ j' gJ"i: TO F O R J i ] I € ~ f ~ f H f I E m ! d " S

89 TOPSEeftl!!!T tJMBRA



: ~

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Vietnam, it had been possible to recognize what information the enemy had wanted and,

by surveying operations, to discover whether that information was being divulged and

how, ifpossible, to prevent it. Away from Vietnam, however, many OPSEC surveys, often of

such operations as wa r game exerc ises , l acked a clear-cut enemy with ident if iable

intelligence interests. In these cases, OPSEC survey teams merely recorded potential

security violations during the exercise, without regard to whether the lapse could have !(b)been exploited by an enemy, or whether it might be correctable, or even whether the 0'

information so divulged would have proved of real interest or value to an enemy.s

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(b ( 3 ) -P .L . 86-36

lOP $I!(RET ~ M I I R A

< Ihas been an i ! l ~ e l l i g e n . c.. eaIlaly.s...t. in the Office

0\~ ( B 5 ) since March 1993.

Pr-evioualyvfrom January 1990 toFebr-uary 1993,he was an

Intelligence Research intern. From 19S7 to 1990 he was a

Secur-ity/Protective Officer with NSA, and from 1984 to 1 9 ~ 1 7 DI Iwas employed by the Federal Bureau of Investigation .

He did research for and wrote this s tudy\while .on a tour with

h n r f. r r tolo ic Histor in 1992. h I

He is professionalized as an Intelligence Research Analyst.

(

(b) (1)

(b) (3 ) -50 USC

(b ) ( 3 ) -P .L . 86

NO I R E L E A ~ A ~ L l ! : 'Fe f 'efttJI8N NltTI8NAI"S

TOP "(RET ~ M B R A 94



"Fep SEERET tJMBRA

DOE

DRV

EAGERYANKEE

ECM

FAC

FOCUS RETINA

FRAGORDER

U.S., Department of Energy

Democratic Republic ofVietnam (North Vietnam)

U.S. coverterm for amphibious assault landing, RVN, 1968

Electronic countermeasures

Forward Air Control

U.S.lROK coverterrn for joint training exercise, ROK, 1969

Fragmentaryorder

(b ) (1 )

( b ) ( 3 ) - 50 USC 40 3(b ) ( 3 ) -P .L . 86-36

HEAVYARTILLERY U.S. coverterm for B-52 strikes

HUMINT Human intelligence

lOSS U.S., Interagency OPSEC Support Staff

JCS U.S., Joint Chiefs of Staff

JGS RVN Joint General Staff

L/H HOUR Helicopter landing/assault boat landing hour

MACV U.S. Military Assistance Command, Vietnam

MAF Marine Amphibious Force

MARKET TI:vrE U.S.lRVN coverterm for coastal interdiction operations, RVN

MIB DRV, Military Intelligence Bureau

MIS DRV,Military Intelligence Section

MRF Mobile Riverine Force

MSD RVN, Military Security Directorate

NCS NSA, National Cryptologic School

NOAC U.S., National OPSEC Advisory Committee

NOTAM Notice to Airmen

NSA U.S., National Security Agency

NSDD National Security Decision Directive

NSG U.S., Naval Security Group

NTDS Naval Tactical Data System

NVA North Vietnamese Army

OPSEC Operations security

PACOM U.S., Pacific Command

NOTRELEASABLE 10 l"5IU3I6U H l r ' f I Q ~ r A IS

"FOP SECRH t:lMBRA 96



T9P S"RET !IMARA

PFIAB

POINT JULIETTE

PRC

PURPLE DRAGON

U.S., President's Foreign Intelligence Advisory Board

U.S. coverterm for B-52 and RC-130 rendezvous point west of the

Philippines

People's Republic ofChina

U.S. coverterm for the first CINCPAC OPSEC survey, 1966-1967,

and unofficial coverterm for CINCPAC's permanent OPSEC

branch,1967-1973

PW

RALLIER

Prisoner ofwar

VCdefector

(b ) (1 )

( b ) ( 3 ) - 50 USC 40 3

(b ) ( 3 ) -P .L . 86-36Republic ofVietnam (South Vietnam)NSA, Communications Security Division

U.S., Strategic Air Command

U.S., Service Cryptologic Agencies

U.S., Senior Interagency Group for Intelligence

Signals intelligence

DRV, Strategic Intelligence Section

Special Landing Force

Signal Operations Instructions

U.S., Strike Command

U.S. coverterm for amphibious assault landing, RVN, 1968

NSA, Technical Instructions

Task Force

Tactical Operations Center

Time Over Target

U.S. coverterm for U.S. Army operation resulting in the capture ofa VC/NVA TRU .

ROK Republic ofKorea (South Korea)

ROLLINGTHUNDER U.S. coverterm for fighter-bomber bombing raids-against DRV,

1965-1968

RVNSl

SAC

SCA

SIG-I

SIGINT

SIS

SLF

SOl

STRICOM

SWIFT SABER

TECHINS

TF

TOC

TOT

TOUCHDOWN

TRU

U&S COMMANDS

UTM

VC

DRV, Technical Reconnaissance Unit

U.S., Unified and Specified Commands

Universal TransverseMercator

Viet Cong

!(tl'f' IUlLrJA:S/rBbEJ 'TO FOag[QPT ~ r! TlQN 4 I 5

97 T9P SECRET UMBRA



fe, SECREf UMBIbIt

Bibliography

!(b) ( 3 ) -P .L . 86-36

Books

Betts, Donzel E. , et al. D ~ a d l y Transmissions: COMSEC Monitoring and Analysis.

National SecurityAgency, CiyptologicHistory Series, 1970, (S NF).

Betts, Donzel E., et al . Working Against the Tide (COMSEC Monitoring an d Analysis).National Security Agency, OryptologicHistory Series, 1970 (TSC NF).

Bowman, John S., General Editor. Th e World Almanac o f the Vietnam War. New York:World Almanac, 1985.

Fulton, William B. Vietnam Studies: Riverine Operations 1966-1969. Washington, D.C.:Department of the Army, 1973.

Lancaster, Bruce. Th e America1'/. Revolution. New York: The American Heritage Library,1971. . .

Newton, Robert E. Th e Capture o f the USS Pueblo an d Its Ef fect on S lGI N T Operations.

Center for CryptologicHistory,1992 (TSC NF NC).- - - = - = - ~ ~ = - = - __: - - ~ : : - - " r T h e Great Conversation: Th e Origins an d Development o f the

National Operations Security Program, Interagency OPSEC Support Staff, 1991.

Sun Tzu. The Art o f War. Trans. Samual B. Griffith, London: Oxford University Press,

1963.

Wallace, Willard M . A p p e a l to Arms: A Military History o f the American Revolution.

Chicago: Quadrangle Books, 1951.

Articles

Deeley, Walter G. "A Fresh Look at PURPLE DRAGON." Signal, Volume 38, Number 8,

April 1984.

1973 (TSC).

L . . . - , : : " , ; " " " T " ' " " _ ~ ~ " " , = , , , = , , ~ r " V i e t Cong SIGINT and U.S. Army COMSEC in Vietnam." Cryptologia,Volume XIII, Number 2, April 1989.

Sawyer, E. Leigh. "Pursuit o f t h ~ r - - - - - " " I Cryptolog, Volume IV, Number 3, March

1979 (TSC).

1 " , , " " , : - = = ~ = = : = : - : - - - - , r " H i s t o r y o f a Dragon." Dragon Seeds, Volume 2, Number III, September.

I..

History (S CCO).

(b ) (1 )

( b ) ( 3 ) - 50 USC 40 3

(b ) (3) -18 USC 79 8

(b ) ( 3 ) -P . L . 86-36

99 TOP SECAHblM8RA



fOP 5!CItI!' l::JMBRA

1\ Interview w i t ~ OH-10-92, Center for Cryptologic- - - - = ' H : : " : ' i s ~ t o - r y - - - - : ' ( S = C - : : : C - : : : O - : - ) . . . . . . L... - - - - I

Other Interviews

NSAProduct

3/00/24596-7 1 2 1 A u g u s t l : : ~ .2I004-70,3? i \PI" i l197m

2J 07'67, 152130ZNove'b

er 67.3/ 09-67,28 August 1967.

' ( b ) ( 3 )- P .L . 86-36

(b ) (1 )

( b ) ( 3 ) -50 USC 40 3

(b ) (3) -18 USC 79 8

NSASources

____ --'!NSA B6, Memorandum WCaptain Smith, JCS J34, 23 August 1972 (SC).

Baker, CharlesW. "Military Effects dfPoor Communications Security - Some HistoricalExamples," (unpublished manuscript) 1991, Center for Cryptologic History (TSC NF).

Betts, Donzel E. The Front 4 Intelligence Threat Puzzle (draft copy), December 1971 (SCNF).

~ . . . . - - - - - : _ - - - . J I C h i e f Sll,\Memorandum to\Distribution .. Subject: COMSEC Thinking of

ExperiencedD;S. ServiceOfficers Assigned-to Vietnam, 18 April 1972 (S CCO).Carter, Lt. Gen. Marshall S;, DIRNSA. Memorandum to Director, CIA, Chief , JCS, andDirector, DIA. Subject: ProjectRATHSKELLER\ 12 January 1968 (TSC).

Chiefof Staff, NSA, Memorandum to Deputy Director, NSA. Subject: OPSEC Task Force

Report. 10 May 1988 (S NFCCOr \

Director for Operations Security, NSA,OPSEC erie£. 1992.

Director for Operations Security,NSA. Chronology of Pre-1984 OPSEC Events andDocumentation. (S NF). . . ,

Director, NSA. Memorandum to N S A R e p r e s e n t a t i v ~ , Pacific Command (NSAPAC), 9August 1966 (SCCO). . . ,

L. . . - I M E l I I 1 ~ r a n d u m t ....', ~ May 1993.

National Security A g e n c y , M e m 9 ~ a n d u m for theChiH, ADSP, Mr. Oliver. Subject:

OPSEC Support, 16 June 1971 (TSCNFLIMDIS CCO), "

(b ) ( 3 ) -P . L . 86-36

J'TQT RgU A lilARhi TO fORiTCN NATION A S

100



T9P SEERI!T l1MBRA

JCS, Memorandum J3M 365 1974 for Distr ibution. Subject: Interim Report, WorldwideOPSEC Conference (Consolidated Conclusions and Recommendations), 26 February 1974(C).

JCS Message 0021 to CINCPAC, 261641Z Jul 72 (SC).

JCS Message 0020 to DIRNSA, 261639Z Jul 72 (SC).

JCS Publication 3.54. Joint Doctrine for Operations Security, 22 August 1991.

JCS Publication 18. Doctrine for Operation Security. 1April 1973 (C).

Smith, St . C. Chairman OPSEC Monitoring Group, Memorandum to Distribution.

Subject: OPSEC Flimsy, 24 August 1972 (C).

U.S. Army Security Agency. TAREX Repor t TCSR 04-71. VCINVA COMINT Effort , 8March 1971 (C).

The White House,Washington, Fact Sheet. National Operations Security Program, 1988.

CINCPAC PURPLE DRAGON Reports

CINCPAC. Operations Security Report, TAB A to Appendix II,l December 1972 (SC NF).

CINCPAC. Operations Security Report, Appendix II , 1 June 1972 (TSC).

CINCPAC S80-00054-71. Operations Security (OP8EC) Report,l December 1971 (T8CNF).

CINCPAC 8S0-00026-71. Operations Security (OP8EC) Report, 1 June 1971 (T8C).

CINCPAC 8S0-00064-70. Operations Security (OP8EC) Report,l December 1970 (TSCNF).

CINCPAC SSO-00048-69. Operations Security (OPSEC) Report,l April 1969 (TSC NF).

CINCPAC 880-00051-68. Operations Security (OP8EC) Report, 1August 1968 (TSC).

CINCPAC 880-00021-68. Operations 8ecurity Report,l April 1968 (T8C).

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US Cryptologic History Series VI, Vol. 2 - Purple Dragon

Documents

Transcript of US Cryptologic History Series VI, Vol. 2 - Purple Dragon