Answer:
The United States found out about Russian nuclear missiles being sent to Cuba in 1962 by using spy-planes.
Explanation:
The discovery of these missiles by the Americans unleashed the Cuban Missile Crisis, a 13-day confrontation between the USSR and Cuba against the United States in October 1962.
It was one of the biggest confrontations in the Cold War. This is usually considered to be the moment when the Cold War was closest to becoming a nuclear conflict. It began on October 14, when the United States discovered and photographied Soviet nuclear missiles, capable of reaching the US territory, stationed in Cuba. The crisis ended on October 28, when USSR leader Nikita Khrushchev ordered the removal of all nuclear missiles against President John Kennedy's promise not to attack Cuba.
