How did the US policy change in the aftermath of World War II, and what roles respectively dd the Cold War and US economic interests play? history

After the failure of the policies of appeasement towards
Nazi Germany in the run up to WWII no political figure in the United States wanted to be
labeled an appeaser.  This led to a vast shift in the focus of US foreign and domestic
policies.

In order to confront and contain communism
(motivated by the domino theory which stated that once one country "fell" to communism
others would follow) the US became a major player in the rebuilding of Europe (the
Marshal Plan) and stopping the spread of communism in the eastern mediterranian
(military aid to Greece).  The US went on to become involved in supporting military
dictatorships across Latin American and Africa and eventually the proxy wars in Vietnam
and Afghanistan.