The announcement of the truman doctrine, the berlin airlift, and the formation of the north atlantic treaty organization were actions taken by the united states to prevent the

To prevent the expansion of communism into Western Europe.

Explanation:

The US Government under the leadership of President Truman had started taking steps to terminate the possibilities of a probable third world war with the view of 'saving the world' from its dreadful consequences. In order to do that, the US had to take certain steps to cease the expansion of communism in western Europe being attempted by Soviet Russia directly or by sponsoring other likeminded neighboring nations to do it.

Protecting and assisting  u.s. citizens  living or traveling abroad; assisting u.s.  businesses  in the international marketplace; coordinating and providing support for international activities of other u.s. agencies (local, state, or federal government), official visits overseas and at home, and other diplomatic efforts.keeping the public informed about u.s. foreign policy and relations with other countries and providing feedback from the public to administration officials.providing  automobile registration  for non-diplomatic staff vehicles and the vehicles of diplomats of foreign countries having  diplomatic immunity  in the united states