The Truman Doctrine The Truman Doctrine was the impetus for the change in United States foreign policy, from isolationist to internationalists; thus we were drawn into two wars of containment and into world affairs. The Truman Doctrine led to a major change in U.S. foreign policy from its inception - aid to Turkey and Greece - to its indirect influence in Korea and Vietnam. The aftermath of World War II inspired the U.S. to issue a proclamation that would stem Communist influence throughout the world. However, our zeal in that achievement sent our soldiers to die in Vietnam and Korea for a seemingly futile cause. It must be the policy of the U.S. to support free peoples. This is no