Cuban Missile Crisis established a naval blockade on October 22 to prevent further missiles from reaching Cuba; Oval Office tapes during the crisis revealed that Kennedy had also put the blockade in place as an attempt to provoke Soviet-backed forces in Berlin as well. The US announced it would not permit offensive weapons to be delivered to Cuba and demanded that the weapons already in Cuba be dismantled and returned to the Soviet Union. After several days of tense negotiations, an agreement was reached between US President John F. Kennedy and Khrushchev. Publicly, the Soviets would dismantle their offensive weapons in Cuba and
Cuban Missile Crisis as "trigger-happy cowboys" who lost Berlin because they could not peacefully resolve the Cuban situation. The EXCOMM then discussed the effect on the strategic balance of power, both political and military. The Joint Chiefs of Staff believed that the missiles would seriously alter the military balance, but McNamara disagreed. An extra 40, he reasoned, would make little difference to the overall strategic balance. The US already had approximately 5,000 strategic warheads, but the Soviet Union had only 300. McNamara concluded that the Soviets having 340 would not therefore substantially alter the strategic balance. In 1990, he reiterated that "it made