Writing anonymously under the pen name "X" in a 1947 issue of Foreign Affairs, Mr Kennan drew the outline of the containment policy:
"It is clear that the main element of any United States policy toward the Soviet Union must be that of a long-term, patient but firm and vigilant containment of Russian expansive tendencies."
Mr Kennan was also instrumental in shaping the Marshall Plan and won a Pulitizer Prize for history and a National Book Award for Russia Leaves the War in 1956. His Memoirs, 1925-1950 won another Pulitzer in 1967. (USAToday)