and digital devices for speeding code-breaking, etc. When the Atlantic convoys of war material from the US to the UK came under serious threat from U-boats, considerable encouragement and practical help was given by the US to accelerate the development of code-breaking machines. Subsequent co-operation led to significant success in Australia and the far East for breaking encrypted Japanese messages. Other technologies Other technologies developed by the British and shared with the Americans and other Allies include ASDIC (sonar), the Bailey bridge, gyro gunsight, jet engine, Liberty ship, RDX, Rhino tank, Torpex, traveling-wave tube, proximity fuze. Technologies developed by the Americans and shared with the British and Allies include the bazooka, LVT, DUKW, Fido (acoustic torpedo). Canada and the U.S. independently developed and shared the walkie-talkie. Legacy The Tizard Mission was the foundation for cooperation in scientific research at institutions within and across the United States, United Kingdom and Canada. Many Norwegian scientists and technologists took part in British scientific research during the period when Germany occupied Norway between 1940 and 1945. This resulted in the Norwegian Defence Research Establishment, formed in 1946. After the war ended, the US ended all nuclear co-operation with Britain. However, the demonstration of British Hydrogen bomb, and the launch of Sputnik 1 by the Soviet Union, both in 1957, resulted in the US resuming the wartime co-operation and led to a Mutual Defence Agreement between the two nations in 1958. Under this agreement, American technology was adapted for British nuclear weapons and various fissile materials were exchanged to resolve each other's specific shortages. Cooperation between British intelligence agencies and the United States Intelligence Community in the post-war period became the cornerstone of Western intelligence gathering and the "Special Relationship" between the United Kingdom and the United States. Many military inventions during the war found civilian uses. See also British Purchasing Commission List of World War II electronic warfare equipment Operations research Radiation Laboratory Telecommunications Research Establishment References Military equipment of World War II United Kingdom–United States relations Soviet Union–United States relations Soviet Union–United Kingdom relations Technological races Science and technology during World War II