<P> The doctrine endured, historian Dennis Merill argues, because it addressed a broader cultural insecurity regarding modern life in a globalized world . It dealt with Washington's concern over communism's domino effect, it enabled a media - sensitive presentation of the doctrine that won bipartisan support, and it mobilized American economic power to modernize and stabilize unstable regions without direct military intervention . It brought nation - building activities and modernization programs to the forefront of foreign policy . </P> <P> The Truman Doctrine became a metaphor for emergency aid to keep a nation from communist influence . Truman used disease imagery not only to communicate a sense of impending disaster in the spread of communism but also to create a "rhetorical vision" of containing it by extending a protective shield around non-communist countries throughout the world . It echoed the "quarantine the aggressor" policy Truman's predecessor, Franklin D. Roosevelt, had sought to impose to contain German and Japanese expansion in 1937 ("quarantine" suggested the role of public health officials handling an infectious disease). The medical metaphor extended beyond the immediate aims of the Truman Doctrine in that the imagery combined with fire and flood imagery evocative of disaster provided the United States with an easy transition to direct military confrontation in later years with communist forces in Korea and Vietnam . By framing ideological differences in life or death terms, Truman was able to garner support for this communism - containing policy . </P>

In what way did the truman doctrine direct the policy of containment