 The blockade limited the showdown to Kennedy and Khrushchev rather than develop into all-out war.Because of Kennedy's tough naval blockade, Khrushchev "directed all Soviet vessels carrying missiles and other military equipment to Cuba to immediately turn back".To intensify the coercive diplomacy strategy, Kennedy shifted from the 'Try-and-See' approach to a hybrid of a virtual 'ultimatum' and a carrot-and-the stick approach.