In the 1950s, the main conservative goal in foreign policy was to prevent communism to spread with the beginning of The Cold War. In the 1980s they were also worried about the spread of communism. For example, the spread of communism in Nicaragua. The main difference between the 1950s and the 1980s is that in the 1980s the topic of conservatives against communism was far more controversial while in the 1950s there was a consebsus about containing the communism.
In the 1950s and in the 1980s conservatives were more interested in foreing policies than in domestic ones. A clear example is President Eisenhower, 1950s, who left domestic affairs to his advisers. In both eras conservatives were eager to avoid socialist ideas but in the 1980s they were more militant.
Vietnam become a single communist nation through the leadership and influence of Who Chi Minh. He embraced communism and he got support from China and Soviet Union to fight the French regime.