Marshall feared that their poverty might make them vulnerable to Soviet wooing, causing them to attach them to communism. America, therefore, felt that it had to preempt potential Russian manipulation by stepping in there first. Although Marshall emphasized that the program was open to all European nations, he structured it in such a way (by making capitalism part of its expected character and linchpin of performance) that it effectively debarred communist-related nations from participating. A few years later, in 1950 Truman expanded his strategy of containment by issuing a report (the NSC-68) that stressed employment of U.S. military to impede communist expansion. Observed the National Security Council:

It was and continues to be cardinal in this policy that we possess superior overall power in ourselves or in dependable combination with other likeminded nations. One of the most important ingredients of power is military strength (Shmoop.com)

To that end, the NSC called for dramatically increased taxes for miliatry purposes and for significat militray buildip.

Describe the effects of these diplomatic efforts for the U.S. And other countries

Russia reacted violently with Soviet Foreign Minister VM Molotov walking out of the conference and forbidding the Soviet bloc from participating. Meanwhile, sixteen Western European nations accepted the aid. The Marshall Plan, as originally intended by America, rebounded for America's benefit, as Western European nations not only found themselves bound by principles of duty and gratitude to America but used their money / aid to buy American goods. America thus consolidated its economic strength and reputation of power nation as a result of this Plan. In fact, the Marshall Plan may quite likely have...

On the other hand, it also lost its dynasty and gained its critics by the Republicans insisting that containment was insufficient. USSR was perceived by America to be too much to a threat to be simply contained by passive means. Eisenhower demanded aggression in order to 'roll back' Communism. Criticism was reinforced by Truman's inability in 'capturing' China from Communist invasion and for losing the Korean War. The Trumann regime, therefore, despite all its successes was shortly after replaced by the Eisenhower era with Eisenhower defeating Adlai Stevenson, the democratic candidate.
Offner (2011) summarizes Truman's Cold War interventions as advancing post war reconstruction in Japan and in parts of Europe, but otherwise intensifying Soviet-American conflict and creating division in Europe, whilst resulting in costly Asian wars that consequented in massive loss of human lives. The result of Truman's Cold War years was ambiguous.

References

Gaddis, J.L. (2005) The Cold War: a new history. New York: Penguin Press

Offner, A. (2011). President Truman and the Origins of the Cold War

BBC

www.bbc.co.uk/history/worldwars/wwtwo/truman_01.shtml

Shmoop Causes of the Cold War

http://www.shmoop.com/causes-of-cold-war/diplomacy.html