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• iliF ID:A2435729 

W' DH.AFT 

The Secretary of War. ~r 1 i,.· 

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I~ ~· stroncly recoWltll4ed ••)ll{"'.;,1utely •••ential \c •ational Det.n•• 

and paticularly ·to the ArJq that/an ~tat• exebane;e ot in:toraatton concendnc 

mil1ta17, military attaahe and diplomatio codes, oipherc, ciphar d.eYioes and 

apparatus ... and code and cipher s711tu• tt1plc7ed b-7 ~. Ita.lJ' and Japu, 

together with dl into?'l&ation oonc•rn1ng the aethods uplo7ed to aolve ••••ac•• , in codes Or ciphers Qf th• oiali•s --~ntioned ch arr~jd bet.we•n the 0oTermHn\9 

ot the Unit.a States and Gr$a.t :Britain. - ·· -~ -~·--·- ---· ·""' ~·--=---=----~~-'--......__ 

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Information which can be fttrni•hed b;r the Unit.a States will 1no1ud• 

Ulotll; oth•r things the details of \he •elutio:a of tu es\ dit:f'louli Japan••• 

machine cipher systea ue•d for Hut:.oftt •eoret8 d1plo11atic .. crespondeno•~which 

ha.a Just CHU OOflpl&'ted by J.nrr Cryptanal.7•\a after •i~hii•en aonths Gf i:m.tensiT• 

vork.1f This exchange is belieTed 83olutaly essi1nti1ll .to •ational U.fenac for the 

following ~ea.sons: ' 

!fr•t• it would prOY1d• '•chnical solution ;ptora~tion. of th• code and 

e1;pher sa;nt••• •plo1ed b7 'h• And.•• and Air rorc•• of the powara in 

qi.uution. Int•reept9d u.terial pel"ta1n1nc thereto i• not now av&ilable. 

:iTen it the interoept.t aa,•ri&l vere obtain.a.bl•• a long period of int•nsive 

atud.1' would be necessary be:f'ore 1<>lu.tion• could b• achieved. In the pre1en\ 

erier,;ency. the saving of time is of 'th• creates\ iaportance. The •%.P•r1encea 

gained b;r the British ia operations .a,;ainat the fcrcoa of th• :power1 in 

queetion slxmld provid• inYaluable intor11a.tion. including oapiured eod•a1 

cipher dnicea, ciphers Md :related docuaents. 

second, 1t would provid• t.Cbnioal solution informa.\ion ot the system• 

employed by the ailitar7 attach••• for•iltl o!fic••~plo•ntic a.nd oonaular 

representatives ot Ge?'Wm7 end Itt..17. This intoraa.tion is ot th• bilh••* 

iaporlance at this ti••• ••peaia.ll:T tor th• d1eclosurea tt •i«ht yield in 

coamcctioa vi th A.Xi• intentions, plan• and oper,g,'t!on• in the C.anal Zou, · Caribbean area and Oan\~al and South .Allerio~. It za;r also disclo•• espionage, 

aabot.,;e plan-. and fifth oolum aot1vi'U~• in thta country and i'is po•••••iona • 

.ldditional itema that might be disclosed ar• the pltuus and intietions of 

a.~ and Ital7 wi \h re9J:)eot to the Par ll'.a•t, ll'\Hsia and the h•nch 

posseadon• 1n the W•st•~ He•i~phere. Al though it aight 'be pc•li ble for 

this Go•emiaent to solve th• ooda and cipher •Y•tu1 in thi• connection 

v1thout the aid of :1nton1ation •xp•cted to be «•1ntd b7 th1• exchange, tu--...._ 

necessary tc obtain IUCh r•aul's aight exteml fro• '.b.tl.lf a 7ear to two 7ears. 

fh• e.:dge:nc1•• of the pre1en\ •m-cen07 torbid weh 4elq. 

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