Lecture origins of the cold war: end of isolationism, fear of another surprise attack, mistake american had made: not joining the league of nations. Collective security: appeasement: have to stand up to aggression right away. Military action: new faith in as well as fear of new technological developments. E. g. atomic bomb: needs to learn how to cope with being a nuclear power, 1949: soviet union develops its own bomb. X : suggested that the way to coexist with the soviets was through containment, had to oppose the expansion of communism. The truman doctrine: support from the united states to countries suffering from oppression from outside powers and are fighting for freedom. The marshall plan: george marshall secretary of state, erp: european recovery plan, more commonly known as the marshall. Plan: plan to send american financial aid to europe to help rebuild after the war.