V.

The Effect of World War II

The United States stayed out of World War II until December 7, 1941, when the Japanese bombed Pearl Harbor, a major American naval base in Hawaii. The attack killed about 3,000 people.

The experience of World War II (1939-1945) changed American attitudes toward isolationism. The United States recognized that to be safe it needed allies. As a result, the country’s postwar policy was based on international cooperation and collective security. The United States was one of four countries to draft the charter for the United Nations (UN) and one of the UN’s founding members. The push by the Soviet Union to increase its sphere of influence changed U.S. foreign policy even further. United States policymakers tried to curtail Soviet expansion and the influence of Communism by giving economic and military aid to other countries. The United States also formed formal military alliances, such as the North Atlantic Treaty Organization (NATO), established in 1949.