Pusan was the last UN stronghold in the Korean War in 1950. The Korean People's Army was severely outnumbered when it finally reached the outskirts, and so the Supreme Commander of the Korean Force, Choi Yong-Kun asked for aid from the Soviet Union and China. The two large Communist Powers agreed, and helped expell the UN Force, and began the Third World War.
In 1971, Pusan fell under the control of the Soviet Union after the successful invasion of Korea during the Purge of the Revisionists. Pusan was later converted into a leading Soviet Naval Base.
In 2006, Pusan was retaken by Soviet forces under the direct orders of Vladimir Putin. From Pusan, the Soviets launched their invasion of Japan. Japan was rendered unable to fight by 2008.