What is meant by the US believed in a policy of containment?

Answer 1

The U.S. believed in the philosophy that the world should avoid another all out war, but also believed that communism and similar government ideals should not be allowed to spread to the many newly deimperialized (for lack of a better word) countries that gained independence from European powers as a result of WWII or the economically damaged countries in Europe from being absorbed into the growing U.S.S.R. The U.S. effectively tried to buy off or bully (maybe a little harsh, but true) anyone who was considering communism or socialism (look at us now), or might give way to anarchy. The Marshall plan was meant to help Europe recover economically and restore its capitalist economy while military involvement throughout Asia (most of which did not succeed - Vietnam/Korea - and caused us to be unable to react to the growing communist party in China) and the Truman Doctrine won the friendship of newly not colony states in Latin America (but really economically made them just as dependent on us as most of them were on the British). This was, in hindsight, an enormous risk on America's side as our economy wasn't very strong at that point either, but it mostly paid off in the end (N. Korea, Cuba, China, and China)

*Note, parenthesis are not necessarily political views, just observations