George F. Kennan, the American diplomat who did more than any other envoy of his generation to shape United States policy during the cold war, died on Thursday night in Princeton, N.J. He was 101. Mr. Kennan was the man to whom the White House and the Pentagon turned when they sought to understand the Soviet Union after World War II. He conceived the cold-war policy of containment, the idea that the United States should stop the global spread of Communism by diplomacy, politics, and covert action - by any means short of war. As the State Department's first policy...