They went crazy bruh, the US began to throw out ideas like the Marshall Plan to help get those countries on their feet, and then the Truman Doctrine to let those countries know that if they need help fighting back, the US will send troops.
Marshall = Money
Truman = Troops
The US would get itself involved in Proxy Wars, which was wars fought in other countries basically that was like basically over democratic vs communism conflict. A great example would be the Korean and Vietnam Wars.
US was scared about the Domino Theory and this meant that if one country became communist all other countries around that country would fall to it too. The US was kinda scared and things in the country wasn’t better because people would go around accusing others that they were communist and something known as the “Red Scare,” happened which was basically a fear of communism. There was, I believe 2 of them, but we also had spies in the country such as the Rosenburgs, but this was like 1915, but they were convicted of being spies, but communism gave America a run for its money as we would do anything to keep it from spreading.