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 wrote, "too young, intellectual, not prepared well for decision making in crisis situations... too intelligent and too weak." US covert operations against Cuba continued in 1961 with the unsuccessful Operation Mongoose. In addition, Khrushchev's impression of Kennedy's weaknesses was confirmed by the President's response during the Berlin Crisis of 1961, particularly to the building of the Berlin Wall. Speaking to Soviet officials in the aftermath of the crisis, Khrushchev asserted, "I know for certain that Kennedy doesn't have a strong background, nor, generally speaking, does he have the courage to stand up to a serious challenge." He also told his