Question

why did the united states believe it was necessary to introduce the truman doctrine and the marshall plan?

Explanation:

The Truman Doctrine (1947) and Marshall Plan (1948) were responses to post - WWII Soviet influence. The US aimed to contain communism: the Truman Doctrine provided military/economic aid to Greece and Turkey to stop communist takeovers. The Marshall Plan offered economic aid to Western Europe to rebuild economies, prevent communist appeal due to poverty, and expand US trade. Also, it was about establishing US dominance in the West and countering Soviet expansion in Europe.

Answer:

The United States believed these were necessary to contain the spread of communism (from the Soviet Union) in Europe and globally. The Truman Doctrine (with aid to Greece/Turkey) and Marshall Plan (economic aid to Western Europe) aimed to: 1. Stop communist takeovers in vulnerable nations (Truman Doctrine). 2. Rebuild Western European economies (Marshall Plan) to reduce poverty - driven communist appeal, secure US trade/security, and establish US influence as a counter to Soviet power in Europe.