The Sources of Soviet Conduct
George Kennan (originally published under the pseudonym "X"), "The Sources of Soviet Conduct," Foreign Affairs, Vol. 65, No. 4 (July 1947), http://bsalanie.blogs.com/Kennan.pdf
From his perspective as a then-young and brilliant U.S. diplomat in Moscow, Kennan outlines the fundamental challenge posed by the Soviet Union's drive for global dominance based on an ideology that was anathema to U.S. interests and principles. His solution became a driver of the policy of "Containment". Based on his then-classified "Long Telegram."