The discovery of characteristic trapezoidal surface-to-air missile sites in Cuba in October 1962 led to an intensive program of high-altitude U-2 overflights and lower-level aerial reconnaissance missions that provided imagery suggesting that Soviet land forces were in the process of constructing launch sites for medium-range ballistic missiles and digging bunkers to store nuclear warheads. Presented with this evidence that Soviet premier Nikita Khrushchev had taken a provocative act, President John F. Kennedy created an Executive Committee at the White House to advise him on how the situation might be resolved. He opted to impose a marine and air quarantine of the island to prevent any further shipments of offensive military matériel.
This unilateral action, supported in principle by Great Britain, France, and Germany but not Canada, resulted in a dangerous confrontation in which merchantmen of various nationalities were threatened in international waters, and three Soviet Foxtrot submarines, of a force of four, each armed with nuclear-tipped torpedoes, were forced to the surface. The fourth Foxtrot, the 911, designated C-20 by the U.S. Navy, evaded the quarantine line until it exhausted its air supply and came up beside the USS Cecil after it had been identified
by the SOSUS station on Grand Turk. Meanwhile, an American U-2 reconnaissance aircraft was shot down and the pilot killed.
Anxious negotiations were conducted via a teleprinter hotline linking the White House to the Kremlin as freighters carrying missiles approached the quarantine line, and the KGB established a back channel through the Washington rezidentura. The result of the talks was a Soviet commitment to dismantle the missile sites and to openly withdraw the offending ballistic missiles and their warheads in such a way that the action could be verified, in return for an undertaking from the United States to remove nuclear missiles from NATO bases in Turkey and Italy and to give an unpublicized, binding guarantee that no attempt would be made in the future to remove Fidel Castro from power.
It was not until a conference was held at Key West in 1992, with many of the surviving participants present, that the Russians disclosed that their submarine flotilla had been armed with nuclear weapons and that, long before the intermediate-range ballistic missiles had been discovered, the Soviet Union had armed the Cubans
with tactical nuclear missiles for use against another invasion. The existence of these weapons, concealed in caves, had remained a closely guarded secret and was never suspected by the Americans.
Furthermore, the Russians revealed that no ballistic missile warheads had reached the ballistic missile launch sites, although they were aboard ships at the docks waiting to be unloaded.