In 1946, the American Chargé d’Affaires in Moscow George F. Kennan proposed the concept of “containment” in his famous 8,000-word  “long telegram” to the U.S. State Department. These suggestions became the foundation of U.S. Cold War policy in the 1940s.

in 1947, under the pseudonym “Mr. X,” Kennan further outlined the concept in an article entitled The Sources of Soviet Conduct  published in the highly-respected political journal Foreign Affairs.

The Russians can’t be trusted and they probably won’t be changed. The main element of U.S. policy toward the Soviet Union, Kennan declared, must be patient but firm and vigilant containment of Russian expansive tendencies.