1946-1953
March 12, 1947, U.S. President Harry Truman announced his intention to give Greek and Turkish military and economic aid worth 400 million dollars. At the same time, he formulated the objectives of U.S. policy that seeks to help "free peoples who are resisting the attempts to enslave by armed minorities and external pressures. Truman in this statement, moreover, determined the content of incipient rivalry between the U.S. and the USSR as a conflict, democracy and totalitarianism. Thus was born the Truman Doctrine, which became the beginning of the transition from post-war cooperation between the USSR and the U.S. to compete.
In 1947, at the insistence of Soviet socialist countries refused to participate in the Marshall Plan, under which the U.S. provides economic assistance to countries affected by war, in exchange for the exclusion of communists from the government.
Efforts by the Soviet Union, in particular Soviet intelligence were designed to eliminate the monopoly of the United States to possess nuclear weapons. August 29, 1949 in the Soviet Union conducted the first test of a nuclear bomb at the Semipalatinsk nuclear test site. American scientists from the Manhattan Project and had warned that, over time the Soviet Union must create its own nuclear capability - however, this nuclear explosion has had a staggering impact on the military strategic planning in the United States - primarily because U.S. military planners did not expect them to will lose its monopoly so soon. At that time was not yet known about the successes of Soviet intelligence, who managed to penetrate into Los Alamos.
In 1948 the U.S. accept "Vandenberg Resolution" - the official denial from the U.S. practice of non-participation in military-political blocs outside the Western Hemisphere in peacetime.
For April 4, 1949 created NATO, and in October 1954 Germany admitted to the Western European Union and NATO. This move provoked a backlash of the USSR. In response to the Soviet Union began to create a military bloc, which would have united the Eastern European countries.
Late 40's - in the Soviet Union begins to repression of dissidents in the U.S. - "witch hunt".
Although the Soviet Union now also has nuclear capability, the U.S. was far ahead of both the number of charges, and the number of bombers. In any conflict the United States easily could have to bomb the Soviet Union, while the Soviet Union could hardly have been able to reply to it.
The transition to widespread use of jet fighter-interceptors somewhat changed the situation in favor of the Soviet Union, reducing the potential effectiveness of the American bombers. In 1949, Curtis Lemay (en: Curtis LeMay), new commander of U.S. Strategic Air Command, signed a program of complete transition bombers on jet thrust. At the beginning of 1950 on arms began to receive B-47 bombers and B-52.
The most acute period of confrontation between the two blocks (the USSR and the U.S. from its allies) took place in the years of the Korean War.