1) President Harry S. Truman established that the United States would provide political, military and economic assistance to all democratic nations under threat from external or internal authoritarian forces.
2) "The Truman Doctrine" was a big deal because it changed the tone and direction of U.S. foreign policy from one of avoiding permanent, entangling alliances to a strategy that emphasized allying with and providing aid to foreign countries. Thanks to "the Truman Doctrine" and its emphasis on engaging in worldly affairs, the Cold War became "hot."