United States Cryptologic History Issues in British and American Signals Intelligence, 1919-1932 Special series | Volume 11 | 2015 Center for Cryptologic History This publication presents a historical perspective for informational and educational purposes, is the result of independent research, and does not necessarily reflect a position of NSA/CSS or any other U.S. government entity. This publication is distributed free by the National Security Agency. If you would like additional copies, please submit your request to: Center for Cryptologic History National Security Agency 9800 Savage Road, Suite 6886 Fort George G. Meade, MD 20755 Cover: The 1921 Washington Naval Conference Issues in British and American Signals Intelligence, 1919-1932 John Ferris SPECIAL SERIES | VOLUME 11 2016 Contents Introduction............................................................................ v Part 1: Reading the World’s Mail: British Censorship, Communications Intelligence, and Economic Warfare, 1914-1919 ............................. 1 Summary ............................................................................... 1 Background ............................................................................ 1 Economic Pressure .................................................................... 2 Blockade Evolution ................................................................... 3 Initial Attempt .................................................................... 3 Legal Basis ......................................................................... 3 Dealing with Neutrals ............................................................ 3 Evolving toward Interdepartmental Use of Intelligence ........................ 4 Enforcing Blockade ................................................................... 6 Evolving Enforcement ................................................................ 6 Intelligence: Evolving to Effectiveness ............................................ 7 Developments in Sources ............................................................ 8 Source I: Statistics ................................................................ 8 Source II: Signals/COMINT ....................................................... 8 Signals Read by Censorship ...................................................... 8 Resulting Data: 1914-1915 ....................................................... 9 Developments in Organization ..................................................... 10 The War Trade Intelligence Department ..................................... 10 WTID Organization ............................................................... 10 WTID Demographics ............................................................. 11 i Issues in British and American Signals Intelligence, 1919-1932 Developments in COMINT: 1914-1916 ............................................. 11 Early in the War .................................................................. 11 Main Source: 1914-1915 ........................................................ 12 Evolving: 1915-1916 ............................................................. 12 COMINT and WTID Information ..................................................... 13 COMINT and Enforcement ...................................................... 13 Intelligence Impacts ................................................................. 14 COMINT and Enforcement ...................................................... 15 Illustration ........................................................................ 15 Limited Impact: Finance ....................................................... 16 Finance: Limits Mitigated .......................................................... 17 Developments 1917-1918 ........................................................... 17 Enforcement Eased .............................................................. 18 Complications in Censorship ................................................... 18 Technical Peak ........................................................................ 19 Conclusions ........................................................................... 19 Notes ................................................................................... 20 Part 2: The Tale of the Trust: The Myth of Soviet Deception of British Intelligence in Russia, 1919-1927 ................................. 23 Summary .............................................................................. 23 The Trust .............................................................................. 23 Influential Idea ................................................................... 24 Cautious View vs. Sensational ................................................. 24 Similar Efforts .................................................................... 24 Known Successes ..................................................................... 24 Short-Lived Success ............................................................. 24 ii Issues in British and American Signals Intelligence, 1919-1932 Sidney Reilly: The Example of a Trust Success .............................. 25 Documentation ....................................................................... 26 UK, SIS Success vs. USSR ........................................................ 26 SIS Istanbul ....................................................................... 27 SIS Section V ...................................................................... 27 SIS Sources in USSR Government .............................................. 28 Agents in Moscow ................................................................ 28 1923-1934: Two Sources ........................................................ 29 Other Sources .................................................................... 30 1923-1930: Main Sources? ...................................................... 30 What Was Reported .............................................................. 30 UK COMINT ............................................................................ 31 Diplomatic COMINT .............................................................. 32 A Trust Attempt?...................................................................... 32 Results of the Attempt .......................................................... 33 SIS Assessment of the Attempt ................................................. 34 Assessment ............................................................................ 35 Riga Authenticity ................................................................ 35 Riga Authenticity: Significance ................................................ 36 Stolen Documents: Authenticity .................................................. 36 Riga: Apparently Authentic .................................................... 36 Self-Assessment of Threat .......................................................... 37 No Threat ......................................................................... 37 No Reflections of Success....................................................... 37 Final Assessment ................................................................. 38 Conclusion ............................................................................ 38 Notes ................................................................................... 39 iii Issues in British and American Signals Intelligence, 1919-1932 Part 3: Gentlemen’s Agreements and Gentlemen’s Mail: Communications Intelligence and The Diplomacy of Naval Disarmament, 1921-1930 ..... 42 Introduction........................................................................... 42 Three Conferences 1921-22 Washington Naval Conference ....................................... 43 Yardley’s Bureau ................................................................. 43 GC&CS ............................................................................. 43 Value in Context ................................................................. 44 1927 Geneva Conference ........................................................... 45 1930 London Naval Conference .................................................... 45 British Prime Minister MacDonald I ............................................ 46 GC&CS’s Opportunity ............................................................ 46 MacDonald II ...................................................................... 46 Two Complex Issues ............................................................. 47 Initial GC&CS Intelligence ...................................................... 48 1930 Conference: First Two Months ........................................... 49 Crisis in the 1930 Conference .................................................. 50 A Japanese Weakness ........................................................... 52 Effects of Communications Intelligence .......................................... 55 Communications Intelligence and Negotiations ............................. 56 Strategic Consequences: Assessment ............................................. 57 Notes ................................................................................... 59 iv Issues in British and American Signals Intelligence, 1919-1932 Introduction tive period, and, better still, with his wide-ranging knowledge about non-COMINT intelligence and The first third of the twentieth century saw the about diplomacy, he has placed this new material in development of modern communications intelli- the proper