Answer:
To prevent the spread of communism in West European nations.
Step-by-step explanation:
The plan by United States to rebuild the economies of allied countries of Europe after the Second world war is called Marshall Plan. The main reason behind Marshall plan was to halt spread of communism.
The plan got its name after George Marshall, he was Secretary of State. The plan began in April 1948 and lasted for four years. Under the plans US spent 13 billion dollars in providing technical and economic help to European countries. The plan successfully uplifted the economy of Western Europe.