Nearing the end of WW2, the Soviet Union invaded Manchuria and Korea to prevent American forces from capturing it. This, plus MacArthur's policy of soft americanisation when he was in charge of the occupation of Japan, transformed Japan into a strong, if sometimes egoistical partner. With South Korea and Taiwan controlled by pro-American regimes, a military bloc was formed in the Pacific, opposed to the threat that China, the Soviet Union, North Korea and now Oceanyka present in the Pacific.
The following nations are members of the PACOP: