Before the 1970s, the Soviet Union was always at a disadvantage economically and militarily, so the United States gained the upper hand. 1962 "Cuban Missile Crisis" ended with the Soviet Union's missile withdrawal, which shows that the Soviet Union still cannot compete with the United States in comprehensive strength. However, after Brezhnev came to power in the 1970s, the Soviet Union's military strength generally caught up with that of the United States because the United States was deeply involved in the Vietnam War. At that time, 1 of every three scientists in the Soviet Union were studying missiles and tanks. In the 1980s, President Reagan put forward the "Star Wars" plan and launched an all-round military competition with the Soviet Union. The Soviet Union was finally dragged down because of the war in Afghanistan and the defects of its own system, and announced its disintegration in 199 1.
Generally speaking, the post-war relationship between the United States and the Soviet Union was a change from a wartime ally to a hegemonic opponent. With the disintegration of the Soviet Union and the collapse of the bipolar structure, this relationship disappeared.