Japanese tanks of World War II M4 Sherman medium tank. Originally, the next tank in development to replace the Type 1 Chi-He was the Type 4 Chi-To medium tank. However, the development of the Type 4 Chi-To was delayed, and a "stopgap tank" was needed. Development of the Chi-Nu started in May 1943 and was finished by October. The low priority given tanks, along with the raw material shortages meant that the Type 3 did not enter production until 1944. It was the last design based directly on Type 97 lineage. The Chi-Nu retained the same chassis and suspension of the Chi-He, but with a new
US signals intelligence in the Cold War continuing the World War II legacy. President Harry Truman, on 24 October 1952, issued a directive that set the stage for the National Security Agency, whose scope went beyond the pure military. NSA was created on 4 November 1952. Air Force SIGINT, by the Air Force Security Service, supported numerous Korean War operations. They often gave early warning of bombing attacks or ambushes for fighter aircraft. Since the North Koreans operated under Soviet doctrine, with strict ground control, the ground-controlled interception communications were especially vulnerable. North Korean orders to bombing units might well be intercepted and processed in the US