Kennedy's speech is critical of soviet-backed actions in what country?

On the late Friday afternoon of July 15, 1960, Senator John F. Kennedy of Massachusetts appeared before a crowd of eighty thousand people in the Los Angeles Memorial Coliseum to deliver his formal acceptance of the Democratic party’s nomination for President of the United States. Before what was at the time touted as the largest crowd ever to hear a political speech,  John F. Kennedy spoke of "the New Frontier"  --a frontier of unknown opportunities and perils-- a frontier of unfulfilled hopes and threats