history help please! fast?

[Jay]

First, start with the situation after WWII where (in broad terms) the world and in particular Europe and Asia were divided between communist and western/liberal democratic free areas with those nations in Europe and Asia on the border. A second problem was that many of these nations suffered extensive damage in WWII and in particular Germany's social and governmental infrastructure had been all but destroyed. Truman appreciated that one of the reasons why WWII happened was because after WWI these nations were given little or no assistance to transition back to peace and develop the necessary institutions that would breed and foster trust and support in the government. So when there were economic problems it became easy for people to support demagogues like Hitler who had populist ideas and supposedly easy solutions. After WWII the fear was that instead of turning to fascism that people would turn to communist totalitarian solutions.

Containment was based on realism - that it would be impossible to roll back communism but it could be stopped and not allowed to spread any further. to this end the "Truman Doctrine" was the overarching policy that essentially laid down the foundations for how the west/USA would deal with communism. That is they would give economic, military and diplomatic aid and support to any nation under threat from a communist insurrection or invasion.

Marshall Aid was the economic arm of this - the bombed out nations in western Europe/Asia were given money to invest in their economies and get them moving again. It also provided a market for US exports and helped the US itseld transition from a wartime to a peacetime economy.

Korea - an example of military/diplomatic support for South Korea after an attempted invasion of the South by the North. Officially this was a UN action rather than a US initiative, but the latter were the main movers in getting UN support and supplied most of the military and financial aid.

Above all Truman wanted to avoid the situation after WWI where the US retreated into isolationism and cut itself off from the world.