HELP In June 1948, Stalin attempted to drive American, British, and French forces out of Berlin, which had been divided among the four powers, by cutting off railway and highway access to the city. In response, U. S. forces used airplanes to drop food and medical supplies to the residents of West Berlin. These airdrops delivered millions of tons of supplies in 1948 and 1949, and the “Berlin Airlift” was hailed as a victory over the U. S.S. R. In 1949, Stalin reopened access routes to Berlin.

In April 1949, at the urging of European nations and in response to concern about communist expansion, the United States, Great Britain, France, Italy, Canada, the Netherlands, Luxembourg, Belgium, Denmark, Norway, Iceland, and Portugal formed the North Atlantic Treaty Organization (NATO). The NATO charter pledged that an attack on one of the member nations constituted an attack on all of the members.

In May 1949, the occupation zones controlled by the U. S., Great Britain, and France officially became the Federal Republic of Germany, which remains the government of Germany today. (East Germany, officially known as the German Democratic Republic, remained within the Soviet bloc until reunification in 1990.)

The United States had demonstrated the strength of its nuclear weapons to the world with the atomic destruction of the Japanese cities Hiroshima and Nagasaki. However, it would not remain the world's sole nuclear power for long. On August 29, 1949, the U. S.S. R. conducted a test of its own A-bomb. A nuclear arms race between the U. S. and the U. S.S. R. commenced, with both countries pouring tremendous resources into increasing the quantity and quality of their nuclear weapons. While neither side ever actually used its bombs against the other, both sides amassed enough of them to completely destroy each other and the rest of the world many times over.

How did these postwar events reflect changes in U. S. foreign policy?