What u. s actions alarmed the Soviet union

The United States was alarmed by Soviet control of Eastern Europe at the end WW II because officials believed Soviet expansion would not stop at Eastern Europe.

Explanation:

The Grand Alliance, otherwise called The Big Three, was a military union comprising of the three significant Allies of World War II: the Soviet Union, the United States, and the United Kingdom. Relations between the Soviet Union and the United States were driven by a perplexing exchange of ideological, political, and monetary elements, which prompted moves between wary collaboration and frequently severe superpower contention throughout the years.