In a dramatic speech to a joint session of Congress, President Harry S. Truman asks for U.S. assistance for Greece and Turkey to forestall communist domination of the two nations. Historians have often cited Truman’s address, which came to be known as the Truman Doctrine, as the official declaration of the Cold War.

In February 1947, the British government informed the United States that it could no longer furnish the economic and military assistance it had been providing to Greece and Turkey since the end of World War II. The Truman administration believed that both nations were threatened by communism and it jumped at the chance to take a tough stance against the Soviet Union. In Greece, leftist forces had been battling the Greek royal government since the end of World War II. In Turkey, the Soviets were demanding some manner of control over the Dardanelles, territory from which Turkey was able to dominate the strategic waterway from the Black Sea to the Mediterranean.

On March 12, 1947, Truman appeared before a joint session of Congress to make his case. The world, he declared, faced a choice in the years to come. Nations could adopt a way of life “based upon the will of the majority” and governments that provided “guarantees of individual liberty” or they could face a way of life “based upon the will of a minority forcibly imposed upon the majority.” This latter regime, he indicated, relied upon “terror and oppression.” “The foreign policy and the national security of this country,” he claimed, were involved in the situations confronting Greece and Turkey.

Greece, he argued, was “threatened by the terrorist activities of several thousand armed men, led by communists.” It was incumbent upon the United States to support Greece so that it could “become a self-supporting and self-respecting democracy.” The “freedom-loving” people of Turkey also needed U.S. aid, which was “necessary for the maintenance of its national integrity.” The president declared that “it must be the policy of the United States to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures.” Truman requested $400 million in assistance for the two nations. Congress approved his request two months later.

The Truman Doctrine was a de facto declaration of the Cold War. Truman’s address outlined the broad parameters of U.S. Cold War foreign policy: the Soviet Union was the center of all communist activity and movements throughout the world; communism could attack through outside invasion or internal subversion; and the United States needed to provide military and economic assistance to protect nations from communist aggression.

Not everyone embraced Truman’s logic. Some realized that the insurgency in Greece was supported not by the Soviet Union, but by Yugoslavia’s Tito, who broke with the Soviet communists within a year. Additionally, the Soviets were not demanding control of the Dardanelles, but only assurances that this strategic waterway would not be used by Russia’s enemies-as the Nazis had used it during World War II. And whether U.S. assistance would result in democracy in Greece or Turkey was unclear. Indeed, both nations established repressive right-wing regimes in the years following the Truman Doctrine. Yet, the Truman Doctrine successfully convinced many that the United States was locked in a life-or-death struggle with the Soviet Union, and it set the guidelines for over 40 years of U.S.-Soviet relations.