In south america, president salvador allende of chile, proclaimed to be a follower of karl marx. why would this concern the u. s. government?

During the Cold War, the “red scare” was alive and well in the west. The Red scare was a phenomen where anything related to, or even a reference, of communism and socialism spread fear and mocking. The United States was scared that Chile could become an Ally of the USSR. (hope this was a help!)