May 17, 1943
Agreement between British Government Code and Cipher School and U.S. War Department concerning cooperation in matters relating to:
U.S. | British |
|---|---|
Special Intelligence A | Special Intelligence |
Special Intelligence B | Y Intelligence |
T A Intelligence | Y Inference |
A distinction is made in nomenclature and procedure in handling intelligence derived from the solution of enemy high grade and that obtained from low grade codes and ciphers. The preservation of secrecy in regard to either category is a matter of great concern to both countries and if the highest degree of security is to be maintained, it is essential that the same methods should be pursued by both countries at every level and in every area concerned, since a leakage at any one point would jeopardize intelligence from these sources not in one area only but in all theaters of war and for all services.
This agreement is limited to the traffic specifically designated herein. It does not cover traffic emanating from non-service enemy or neutral sources. These subjects will be covered by future negotiations between Director, G.C.&C.S. and A. C. of S., G-2, War Department.
(1) Both the U.S. and British agree to exchange completely all information concerning the detection, identification and interception of signals from, and the solution of codes and ciphers used by, the Military and Air forces of the Axis powers, including secret services (Abwehr).
(2) The U.S. will assume as a main responsibility the reading of Japanese Military and Air codes and ciphers.
(3) The British will assume as a main responsibility the reading of German and Italian Military and Air codes and ciphers.
(4) Both countries agree that special security regulations shall apply to Intelligence obtained from decoding telegrams in enemy high grade codes and ciphers.
(5) Both countries agree to use their most secure codes and ciphers for transmission of the decodes of enemy signals and transmission of technical cryptanalytic data.
(6) British or U.S. Commanders-in-Chief, Military or Air, will receive all Special Intelligence necessary to them for the conduct of their operations from either British or U.S. centers as maybe mutually agreed. Liaison officers will be appointed as desired for facilitating this. They will be given full access to all decodes.
(7) The distribution of intelligence from the sources in question will be governed by the fundamental principle that distribution will be restricted to the minimum and will therefore be confined solely to those who require to receive the intelligence for the proper discharge of their duties.
(8) All recipients of Special Intelligence A, whether British or American officers, shall be bound by the same regulations, the regulations [Appendix (B)] now in force in the theaters of war where British forces are operating to be accepted at the present time. If at a later date either country wishes to modify them in the light of further experience then this may be done by mutual agreement.
(9) The extension to officers of a knowledge of the existence of such intelligence shall be confined to as limited a number as possible and restricted to the levels of command in conformity with the above mentioned regulations. Great stress is laid on the principle that Special Intelligence A should not be intermingled in reports with general intelligence from other sources. If, however, it becomes imperative to do so, the whole must be treated as Special Intelligence A and given the same strictly limited distribution. Under no circumstances is it permissible to pass Special Intelligence A in a code or cipher which can be read by other than the authorized recipients.
(10) Although Special Intelligence B is not subject to the same stringent regulations as Special Intelligence A, since the two are closely connected, it is essential to maintain a high degree of secrecy in the handling of Special Intelligence B also. In any action taken upon such intelligence and in any documents or telegrams based upon it, it is essential that its origin be disguised and that the codes or ciphers used for its dissemination be absolutely secure.
(11) All intelligence available from decodes shall be made available to Liaison Officers, and if they deem necessary it will be exchanged between London and Washington. These Liaison Officers will be specially appointed and given full facilities for this purpose.
(12) British and U.S. will notify one another without delay, giving full particulars, when either has information from any source indicating the compromise of any code or cipher used by the other. Action on such information will be most carefully considered in order not to compromise the source and if possible mutual agreement in such action will be sought.
(13) Cooperation between and coordination of U.S. Signal Intelligence Service and British "Y" Service must take place at all levels, technical information being exchanged mutually at the same level and each country to agree not to lower the classification of such information or the intelligence derived from it below that level without mutual agreement.
(14) Each country shall inform the other of the employment and scope in each joint theater of war of their Signal Intelligence (Y) units in the field.
(15) This agreement or the appendices thereto may be supplemented or modified from time to time governing any special feature for which either party wishes to make special provision.
(16) Definitions:
(a) Y Service or Signal Intelligence Service. The British, U.S. Army, and the U.S. Navy services concerned with intercepting, decoding, interpreting, classifying and dissemination of enemy (and neutral) communications, and the use of D/F and other specialized apparatus for establishing locations and identities of enemy transmitters.
(b) Special Intelligence A. Certain ciphers are placed in a special category, owing to their importance and difficulty of solution. The intelligence derived from these ciphers is known as Special Intelligence A. Such material is treated with most stringent security measures. Special Intelligence A is confined to a very strictly limited number of the most highly placed officers and is mainly of strategical importance.
(c) Special Intelligence B. Intelligence derived from the solution of lower grade ciphers. Such ciphers may under certain circumstances be upgraded to the "Special A" class. The dissemination of Special Intelligence B is wider though always treated as British Most Secret-U.S. Secret. Special Intelligence B may be used tactically.
Appendix (A) Special Provisions Regarding Work on German Machine Ciphers
(U) Since it is believed unnecessary and impracticable to duplicate work on German machine ciphers and in view of the large number of personnel required and the unavoidable extra risk to the security of the source involved, agreement which follows has been arrived at. This agreement provides that:
(a) All desired intelligence from this source will be made available to the War Department in Washington.
(b) U.S. personnel will obtain experience by engaging in the solution of this type of cipher in Great Britain.
(c) Research into new methods of attack will be made in Washington.
(d) Transmission of Intelligence to Commanders-in-Chief in the field will be accomplished by special routes and staffs who will maintain a watch over the use of the intelligence to guard against compromise of the source.
(1) U.S. liaison officers will be appointed at G.C.&C.S. to examine messages and summaries and select those desired for transmittal to Washington for G-2 or the Theater Commanders. All decoded material will be made available to those officers. Decodes giving information regarding Order of Battle will be handled as at present, i.e., through U.S. liaison officers in War Office and Air Ministry, respectively.
(2) Decodes or summaries to be passed to Washington through existing British channels.
(3) U. S. party to effect independent solution of keys will be established in Great Britain, but so coordinated by mutual agreement to avoid duplication. This party will cooperate with the British in regard to tasks and will be given every assistance for instruction of personnel. They will be furnished with British machines. Decodes from this section will be passed to Bletchley Park for emendation, translation and distribution, but U.S. party will conduct complete processing, including emendation and translation to such an extent as they desire.
(4) Formulas will be supplied by Great Britain for use on machines now at Arlington Hall.
(5) U.S. to undertake research for finding a new method for solution and to be rendered every assistance by the British for this purpose.
(6) In conformity with British policy, U.S. personnel engaged in solution work in Great Britain will not be transferred elsewhere except for very urgent reasons.
(7) Special Intelligence from this source will be passed to Commanders-in-Chief in the field through the Special British units provided for this purpose. The officer in command of these units will have direct access to the Commander-in-Chief and advise as necessary on the security aspect of handling and using this intelligence. Where an American officer is Commander-in-Chief, an American officer, properly trained and indoctrinated at Bletchley Park, will be attached to the unit to advise and act as liaison officer to overcome difficulties that may arise in regard to differences in language.
(8) The Director of the G.C.&C.S. will have the final decision when matters of security are involved in intelligence items (gossip) and as to what is passed to Commander-in-Chief in the field.
Appendix (B) British Security Regulations for Special Intelligence Part I Coordination of Routing, Security and Use of Special Intelligence
1) SPECIAL INTELLIGENCE is the agreed name for the highly secret information obtained by cryptographic means from enemy high grade ciphers.
2) Lower grade cryptographic material classed in general as "Y" Intelligence, is not included in the definition of SPECIAL INTELLIGENCE.
Part I to be Destroyed by Fire when Read
Part II
1) ALL SPECIAL INTELLIGENCE emanating from the United Kingdom and transmitted to Commands abroad will receive the prefix "Ultra."
ALL SPECIAL INTELLIGENCE emanating from centres other than the United Kingdom and transmitted either to United Kingdom or to another Command abroad, is to receive the prefix specially allotted to each producing centre as follows:
DELHI
Prefix
SIRDAR
WASHINGTON
Prefix
ZYMOTIC
MELBOURNE
Prefix
ZYMOTIC
KILINDINI
Prefix
ZYMOTIC
MIDDLE EAST
Prefix
SWELL
3) SPECIAL INTELLIGENCE produced by U.S.A. centres either in U.S.A. or elsewhere if transmitted over British routes either to the United Kingdom or to the British Commands overseas, is to receive the prefix of the Command or centre through which it is distributed.
4) Where it is necessary for SPECIAL INTELLIGENCE to be transmitted between Commands or centres other than the United Kingdom, special routes and ciphers are to be arranged and approved by London.
Part III
ULTRA (see Para. 1) above) information can be regarded as reliable and action can be taken on it, but experience has shown that the following security regulations are vital to the preservation of this source. The Commander-in-Chief is held personally responsible for ensuring that they are scrupulously adhered to:
(1) The utmost secrecy is to be used in dealing with ULTRA information. Attention is called to the fact that if from any document that might fall into the hands of the enemy or from any message that the enemy might intercept, from any word that might be revealed by a prisoner of war, or from any ill-considered notion based upon it, the enemy were to suspect the existence of the ULTRA source, that source would probably forever be lost to our cause.
(2) This loss would vitally affect operations on all fronts, not only the particular front on which the source had been compromised.
(3) Commanding Officers of those Commands authorized to receive ULTRA information, i.e., normally only General and Air Officers commanding Armies and Air Forces, are to be instructed that ULTRA messages are for them, their personal representative, and their Senior Intelligence and Operations Staff Officer only, and are not to be seen by, read to, or discussed with any other person. ULTRA messages are to be destroyed by fire immediately [once] action has been taken on them. No records of Intelligence based on ULTRA information may be kept except at the H.Q. of the Commander-in-Chief.
(4) When ULTRA information is to be used by the Commander of an Army or an Air Force as a basis for action to be taken by a subordinate command, the information must be translated, when passed to the subordinate command, into terms of an operational order, so worded that if captured or intercepted by the enemy the origin of the information could not be traced back to the ULTRA source, e.g., orders must never contain the precise time, date or place of an enemy operation revealed by ULTRA. Such orders based on ULTRA information if transmitted by WIT must be encoded only in authorized ciphers. Under no circumstances whatever is it permissible to transmit ULTRA information as such to lower formations.
(5) In general, if any action is to be taken based upon ULTRA information, the local Commander is to ensure that such action cannot be traced back by the enemy to the reception of ULTRA intelligence alone. A momentary tactical advantage is not sufficient ground for taking any risk of compromising the source. No action may be taken against specific sea or land targets revealed by ULTRA unless appropriate air or land reconnaissance has also been undertaken. Names of enemy ships revealed by ULTRA sources may never be quoted.
(6) The utmost care is to be taken in briefing pilots for an operation based on ULTRA information that only such details are given them as might have been obtained by other means, such as air reconnaissance, and only such as are essential to the success of the operations.
(7) No reference to ULTRA information is to be made in any summary whatsoever, however limited the circulation. No discussion of it is permissible except between the senior officers who are immediately concerned with the action to be taken upon it.
(8) If it is necessary to ask questions, or make comments on ULTRA material, whether on matters of Intelligence, Operations, Routing or Security, such messages are to be transmitted only over the special channel and in the special ciphers provided for ULTRA traffic.
(9) Recipients of ULTRA may not under any circumstances carry on their persons outside their Headquarters, ULTRA messages which have been delivered to them.
1st March 1943
(Sgd.) GEO V. STRONG
Major General
A.C. of S., G-2
(Sgd.) E. W. TRAVIS
D.D.(S)
G.C.&C.S.
15 June 1943
Approved for the U.S. War Department.
By order of the Secretary of War.
(Sgd) JOSEPH T. McNARNEY,
Lieutenant General, U.S. Army,
Deputy Chief of Staff