The central event of the Cuban Missile Crisis in 1962 was the discovery of Soviet nuclear missiles in Cuba, which prompted a tense standoff between the United States and the Soviet Union. In October 1962, U.S. reconnaissance flights revealed the missiles, leading President John F. Kennedy to impose a naval blockade, referred to as a "quarantine," to prevent further shipments. For thirteen days, the world faced the threat of nuclear war as negotiations ensued between the two superpowers. The crisis ultimately ended with the Soviet Union agreeing to withdraw the missiles in exchange for a U.S. promise not to invade Cuba, highlighting the perils of Cold War brinkmanship.