The 1940 Summer Olympics, officially known as the Games of the XII Olympiad, was a planned international multi-sport event scheduled to have been held from September 21 to October 6, 1940 in Tokyo City, Empire of Japan, and later rescheduled for July 20 to August 4, 1940 in Helsinki, Finland following the outbreak of the Second Sino-Japanese War in 1937. They were ultimately canceled because of World War II alongside the 1940 Winter Olympics in Sapporo, Empire of Japan, and were the third games to be canceled due to war.

The 1964 Summer Olympics , officially the Games of the XVIII Olympiad and commonly known as Tokyo 1964, were an international multi-sport event held from 10 to 24 October 1964 in Tokyo, Japan. Tokyo had been awarded the organization of the 1940 Summer Olympics, but this honor was subsequently passed to Helsinki due to Japan's invasion of China, before ultimately being cancelled due to World War II. Tokyo was chosen as the host city during the 55th IOC Session in West Germany on 26 May 1959.