REF ID:A488574 

Declassified and approved for release by NSA on 11-06-2013 pursuant to E .0. 1352\3 
REF ID:A488574 

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ARMY SERVICE FORCES --,A/ ~~ SIGNAL SECURITY AGENCY 

WASHINGTON 28, D. C, 

SPSIB-4 14 May 1945 

SUBJECT: Intercept Assignment at Monitor Station 

THRU: Chief, Intelligence Division, SPSIS-9 

TO: Director of COIJIDllllications Research, SPSIS-.3 

1. Attached as Tab t1A11 is the intercept mission in effect at Monitor 

Station Five during December 1941. 

2. Tab "A" includes an outline of the intercept and traffic forwarding directive in effect at Monitor Station Five on 1 December 1941, 

together with all changes made during that month. Tld.s outline was prepared 

from a basic assignment dated 7 October 1940 which superseded all previous 

assignments to that station, and subsequent changes thereto which were sent 

by radiogram. Two radiograms, dated 1 April 1941 and 17 Jllll.e 1941, are 

missing. Efforts are being ma.de to locate these in the War Department 

Classified Message Center. 

3. A summary of the intercept traffic received from Station Five 

during December 1941 is available if desired. This summary has been prepared from log sheets furnished by that station which listed each message 

individually together with the following identifying items: 

a. Address 

b. Sending and receiving call signs 

c. City of origin 

d. First two groups of texts 

e. Signature 

4. This information was obtained from material in the Communications 

Branch central file. These files are being retained temporarily in SPSIB-4 

and are available for your inspection. __ 

1 Incl 

Tab "A11 

SEGREI 

~~~ Major, Signal Corps 

Chief, Traffic Analysis 

and Control Branch 
• 

Sitithn :A488574 

TAB "A" 

1. Intercept Assignment of Monitor Station 5 as of 1 December 1941: 

a. Coverage 

First Priority 

1. Berlin to Tokyo 

2. Rome to Tokyo J. Far :Eastern Diplomatic Net, including: 

Tokyo to Shanghai 

Shanghai to Tokyo 

Tokyo to Tientsin 

Tientsin to Tokyo 

Tolqo to Peking 

Peking to Tokyo 

Tokyo to Hsinldng 

Hsinldng to Tokyo 4. Batavia to Tokyo 5. Tokyo to Batavia 

6. Bangkok to Tokyo 

7. Tokyo to Bangkok 

Second Priority 

1. Tokyo to London 

2. Tokyo to Hanoi 

J. Tokyo to Rome 

4. Tokyo to Geneva 

Search 

1. Japanese Broadcast of Government Code 

Long Wave 

1. DFY (Berlin) 1'irst priority 

JND (Osaka) first priority 

2. Others, as heard - second priority 

It copying an assigned circuit, and covered end works into a 

different circuit, copy the new circuit. 

Methods of Forwarding to SIS 

1. Japanese dip code 

with single 5-

digit indicator, 

except RIKUGUN.* 

Clipper Mail 

1. German dip letter 

traf 1'ic having no 

.Q or .!!· 

SEBREJ 

Registered (Boat) Mail 

1. Japanese "LA 1

1 traf !ie. 

2. Japanese Military 

A-ttache HEIWA traffic. 
• 

• 

Methods of Forwarding to SIS (cont'd) 

Clipper Mail Registered (Boat) Mail 

2. Japanese code 

broadcast picked 

up on search. 

2. German Military 

Attache. 

3. Japanese Military 

Attache plain text. 

3. Italian "10 letter" 3. 

traffic. 

4. Japanese diploma.tic 

traffic having indicator group BYGAB 

within first six 

groups of text. This 

traffic further 

identified by fivedigi t group near end 

of message. 

All Japanese dip- 4. 

lomatic, except for 

types specified 

under "Radio" or 

"Registered Mail"•* 5. 

German, Italian, 

Mezican Government 

plain text. 

All other traffic. 

* Under definitions of traffic types as understood by the intercept 

stations, "Japanese diplomatic" would include Japanese Military Attache 

traffic. 

2. Changes in Intercept Assignment Made 1-31 December 1941: 

a. 2 December: Copy all Japanese diplomatic plain text. (kit. 2) 

b. 2 December: Forward by air nail all Japanese diplomatic '7 traffic not specified for forwarding by ~ 

radio. 

c. 7 December: Forward by priority enciphered radio all 

Japanese plain text messages ending with (Att-.3) 

the English word STOP.