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 S-75 Dvina (NATO designation "SA-2") surface-to-air missile sites at eight different locations. CIA director John A. McCone was suspicious. Sending antiaircraft missiles into Cuba, he reasoned, "made sense only if Moscow intended to use them to shield a base for ballistic missiles aimed at the United States." On August 10, he wrote a memo to Kennedy in which he guessed that the Soviets were preparing to introduce ballistic missiles into Cuba. With important Congressional elections scheduled for November, the crisis became enmeshed in American politics. On August 31, Senator Kenneth Keating (R-New York), who received his information from Cuban exiles