U.S. Army intelligence officials were told that China, the Soviet Union and North Korea planned to invade Japan during the Korean War, according to documents uncovered by Kyodo News at the National Archives in London.

An unnamed source told the officials that the three countries were to attack Japan by air and submarine and that the assault would also involve an invasion of Taiwan.

The informer said Joseph Stalin, Kim Il Sung and Mao Zedong met in Moscow for around five days to formalize the plan on or around Dec. 3, 1950. They also discussed strengthening their alliance and agreed to complete their occupation of South Korea by April 1951.