that Castro's new administration should be helped economically and politically, but there was still talk of military assistance. Washington's increasing economic embargo led Cuba to seek new markets in a hurry to avert economic disaster. Castro asked for help from the Soviets, and in response, Khrushchev approved the temporary purchase of Cuban sugar in exchange for Soviet fuel. The deal was to play a part in sustaining the Cuban economy for many years to come. It also would play a role in the Soviet economy, with Cuban sugar becoming widely available even during frequent shortages of other food products. After the failed Bay of Pigs Invasion of 1961, Castro announced publicly that Cuba was to become a socialist republic. Khrushchev sent congratulations to Castro for repelling the invasion but privately believed that the Americans would soon bring the weight of their regular army to bear. The defense of Cuba became a matter of prestige for the Soviet Union, and Khrushchev believed that the Americans would block all access to the island by sea or by air. Cuban Missile Crisis Khrushchev agreed on a deployment plan in May 1962, primarily in response to Castro's fears over yet another American invasion, and by late July, after signing the Soviet-Cuban Friendship, Cooperation and Mutual Defence Treaty, over 60 Soviet ships had been en route to Cuba, some of which were carrying military material. Khrushchev and Castro planned to secretly establish a Soviet Armed Forces presence on the island before announcing a defense pact once nuclear-armed ballistic missiles were installed and targeted at the United States. A U-2 flight on the morning of October 14 photographed a series of surface-to-air missile sites being constructed. In a televised address on October 22, US President John F. Kennedy announced the discovery of the installations and proclaimed that any nuclear missile attack from Cuba would be regarded as an attack by the Soviet Union and would be responded to accordingly. The Cuban Missile Crisis became the peak of Soviet-Cuban diplomatic friendship and military cooperation. The Castro brothers and Che Guevara became popular figures among the Soviet public, who believed they were reminiscent of the leaders of the Russian Revolution. However, Castro unnerved the Soviet Politburo with his belligerent attitude towards the crisis, urging the Soviet Union to launch a preemptive nuclear strike to annihilate the United States. Khrushchev sent letters to Kennedy on October 23 and 24