Cuban Missile Crisis forces. Kennedy met with members of EXCOMM and other top advisers throughout October 21, considering two remaining options: an air strike primarily against the Cuban missile bases or a naval blockade of Cuba. A full-scale invasion was not the administration's first option. McNamara supported the naval blockade as a strong but limited military action that left the US in control. The term "blockade" was problematic. According to international law, a blockade is an act of war, but the Kennedy administration did not think that the Soviets would be provoked to attack by a mere blockade. Additionally, legal experts at the
Cuban Missile Crisis U-2 by a Soviet missile violated direct orders from Moscow, and Cuban antiaircraft fire against other US reconnaissance aircraft also violated direct orders from Khrushchev to Castro. Second, the Soviets already had 162 nuclear warheads on Cuba that the US did not then believe were there. Third, the Soviets and Cubans on the island would almost certainly have responded to an invasion by using those nuclear weapons, even though Castro believed that every human in Cuba would likely die as a result. Khrushchev also knew but may not have considered the fact that he had submarines armed with nuclear weapons