 After the convictions , the Cold War continued in the international arena . In December 1950 , Truman declared a national emergency in response to the Korean War . The First Indochina War continued in Vietnam , in which communist forces in the north fought against French Union forces in the south . The US expanded the Radio Free Europe broadcasting system in an effort to promote Western political ideals in Eastern Europe . In March 1951 , American communists Julius and Ethel Rosenberg were convicted of spying for the Soviet Union . In 1952 , the US exploded its first hydrogen bomb , and the Soviet Union followed suit in 1953 . 
