The Cuban Missile Crisis was one of the United States direct and most dangerous confrontation that almost lead to a nuclear war against the Soviet Union during the Cold War period. The failed attempt to overthrow the Castro regime in Cuba in 1961 with operation Bay of Pigs, lead to him creating a closer tie with the Soviet Union. In July of 1962, Soviet premier Nikita Khrushchev made a secret agreement to place Soviet nuclear missiles in Cuba to avert future invasion attempts (The Presidencies, pg. 13). Because of this agreement the following thirteen days in history was built with the most tension of whether or not this would be the end of he world to a nuclear holocaust. U.S. intelligence discovered the missiles in Cuba alerting President Kennedy, whom issued a public warning against the introduction of offensive weapons into Cuba (The Presidencies, pg. 13). President Kennedy ordered for a naval quarantine of Cuba, making a blockade around the island to prevent supplies from coming in and out from the Soviet Union to help continue the support of building the missiles. He also reached out to the Soviet Union asking for them to dismantle and remove the missiles or the United States will have no choice but to attack Cuba. Khrushchev responded in October to President Kennedys message stating this was an act of aggression and for the Soviet ships heading to Cuba to be allowed to proceed. Both sides was head strong on their ends until they came to an agreement shortly after. The United States requested for the Soviet Union to dismantle and removal all the missiles back to the USSR where as, the Soviets insisted the United States remove the missiles in Turkey to reach the agreement. Due to these events, prevention of another war took place along with agreements to a nuclear Test Ban Treaty and the establishment of an open telephone link between the White House and the Kremlin to make contact direct and simpler.
Reference;
The presidencies of John F. Kennedy and Lyndon B. Johnson. (2013, October 31). Milestones: 19611968. Retrieved from https://content.umuc.edu/file/8b0301b2-6d9b-4c9a-9386-3c6936972e19/1/ThePresidenciesofJohnFKennedyandLyndon.pdf.