Canada in the Cold War in power believed that as long as the US president retained absolute control of the nuclear weapons, Canadian forces could be ordered to undertake nuclear missions for the US without Canadian consent. During the Cuban Missile Crisis, Canada was expected to fall in line with American foreign policy, in that Canada's military forces were expected to go on immediate war alert status. Diefenbaker however, refused to do so emphasizing the need for United Nations intervention. It would only be after a tense phone call between President John F. Kennedy and Diefenbaker that Canada's armed forces would begin preparations for "immediate
Cuban Missile Crisis U-2 by a Soviet missile violated direct orders from Moscow, and Cuban antiaircraft fire against other US reconnaissance aircraft also violated direct orders from Khrushchev to Castro. Second, the Soviets already had 162 nuclear warheads on Cuba that the US did not then believe were there. Third, the Soviets and Cubans on the island would almost certainly have responded to an invasion by using those nuclear weapons, even though Castro believed that every human in Cuba would likely die as a result. Khrushchev also knew but may not have considered the fact that he had submarines armed with nuclear weapons