World War I marked a temporary window for a foreign policy motivated in part by Wilsonian idealism as exemplified by the Fourteen Points. But this was only temporary, and quickly gave way to a new isolation in which the United States made avoiding European politics and economic protectionism its primary foreign policy objectives. The advent of the World War II was the crucial foreign policy event of the century in that it paved the way for a new internationalism. After the war, the United States supported, and took leading roles in, institutions such as the United Nations and the International Monetary Fund (IMF.) The US also took a leading role in encouraging European economic recovery, which was part of a larger foreign policy initiative known as containment. Containment entailed resisting the spread of communism, which led to standoffs in Germany and Cuba and open conflicts in Korea and Vietnam. The Cold War also saw the United States attempting to influence politics in the developing world through the deployment of aid and sometimes military intervention, also as part of the fight against communism. Beginning in the 1970s, the United States and Soviet Union entered a phase known as detente, in which both parties essentially recognized the legitimacy of the other and sought to defuse tensions. This policy gave way to a new approach ushered in by Ronald Reagan that sought to roll back communism in eastern Europe and even within the Soviet Union itself.