Actually the US ruling class knew very well that what existed in the old USSR wasn’t socialist.
In 1959 one of the members of the Russian ruling elite, Mikoyan, visited the USA. On his departure he gave a farewell message in which he described Russia as socialist. The US Secretary of State, the notorious John Foster Dulles, replied on behalf of President Eisenhower:
“The President is aware that you operate under a system of State capitalism . . .”
See here.