Answer :

The secret agreement ending the Cuban Missile Crisis (also known as October Crisis, Caribbean Crisis or The Missile Scare) took place in July 1962 between Nikita Khrushchev and Fidel Castro. On that day Khrushchev agreed to Castro's request to place nuclear weapons on Cuban territory in order to withhold potential persecutions of Cuba in the future. New missile sites started appearing a few weeks later.

a promise by the United States not to invade Cuba again.