After the Second World War, America and its allies needed a new plan to deal with the Soviet Union. They saw two choices ahead – another world war or appeasement. A third option came from an obscure U.S. diplomat named George Kennan. His strategy to confine Russian expansion would define America’s relationship with the Soviet Union for nearly half a century. But Kennan would come to regret the policy that made him the most influential diplomat of the Cold War. It led to conflicts in Korea and Vietnam and even to U.S. entanglements in Iraq and Afghanistan. The legacy of America’s Cold War containment strategy.