Relations with the United States deteriorated further in 1961 when the U.S. supported CIA-trained anti-Castro exiles in the Bay of Pigs invasion – a failed attempt to overthrow Castro and a major blow for President Kennedy. In this context, in the summer of 1962 Castro accepted the Soviet offer to install missiles in Cuba as a deterrent to a U.S. invasion. During the crisis Castro urged Khrushchev to defend Cuba and reject American demands to withdraw the missiles. On October 27, believing a U.S. attack was imminent, Castro urged Khrushchev to initiate a nuclear first strike. Castro was excluded from the negotiations and felt that, by agreeing to withdraw the missiles, the Soviets had betrayed Cuba.