George Kennan, the American charge d’affaires in Moscow, sends an 8,000-word telegram to the Department of State detailing his views on the Soviet Union, and U.S. policy toward the communist state. Kennan’s analysis provided one of the most influential underpinnings for America’s Cold War policy of containment.

Kennan was among the U.S. diplomats to help establish the first American embassy in the Soviet Union in 1933. While he often expressed respect for the Russian people, his appraisal of the communist leadership of the Soviet Union became increasingly negative and harsh. Throughout World War II he was convinced that President Franklin D. Roosevelt’s spirit of friendliness and cooperation with Soviet leader Joseph Stalin was completely misplaced. Less than a year after Roosevelt’s death, Kennan, then serving as U.S. charge d’affaires in Moscow, released his opinions in what came to be known as the “long telegram.”

The lengthy memorandum began with the assertion that the Soviet Union could not foresee “permanent peaceful coexistence” with the West. This “neurotic view of world affairs” was a manifestation of the “instinctive Russian sense of insecurity.” As a result, the Soviets were deeply suspicious of all other nations and believed that their security could only be found in “patient but deadly struggle for total destruction of rival power.” Kennan was convinced that the Soviets would try to expand their sphere of influence, and he pointed to Iran and Turkey as the most likely immediate trouble areas. In addition, Kennan believed the Soviets would do all they could to “weaken power and influence of Western Powers on colonial backward, or dependent peoples.” Fortunately, although the Soviet Union was “impervious to logic of reason,” it was “highly sensitive to logic of force.” Therefore, it would back down “when strong resistance is encountered at any point.” The United States and its allies, he concluded, would have to offer that resistance.

Kennan’s telegram caused a sensation in Washington. Stalin’s aggressive speeches and threatening gestures toward Iran and Turkey in 1945-1946 led the Truman administration to decide to take a tougher stance and rely on the nation’s military and economic muscle rather than diplomacy in dealing with the Soviets. These factors guaranteed a warm reception for Kennan’s analysis. His opinion that Soviet expansionism needed to be contained through a policy of “strong resistance” provided the basis for America’s Cold War diplomacy through the next two decades. Kennan’s diplomatic career certainly received a boost–he was named U.S. ambassador to the Soviet Union in 1952.

After leaving government service, Kennan served on the faculty of the Institute for Advanced Study until his death in 2005 at the age of 101.