Containment Takes Shape: The Truman Doctrine, the Marshall Plan, and Kennan

George F. Kennan, an American diplomat stationed in Moscow, first formulated the doctrine of containment in his "Long Telegram" of February 1946 and developed it publicly the following year in the article "The Sources of Soviet Conduct," published under the pseudonym "X." Kennan argued that Soviet behavior stemmed from a combination of Marxist-Leninist ideology and a deep-seated historical Russian insecurity, and he proposed containing Soviet expansion through sustained political and economic pressure rather than direct war, believing that the Soviet system carried "the seeds of its own decay" over the long run.