Final answer:
The U.S. invasion planned for October 1962 amid the threat of nuclear war, but never executed, was targeted at Cuba during the Cuban Missile Crisis.
Step-by-step explanation:
The planned U.S. invasion of an island amid the threat of nuclear war in October 1962, which ultimately never happened, was aimed at Cuba. The world watched anxiously during this period, which is well-known as the Cuban Missile Crisis. After U.S. military officials advised President Kennedy to strike Cuba before nuclear missile silos became operable, Kennedy opted to declare a quarantine zone around the island and announced the discovery of the missile silos on television, preventing a likely escalation to nuclear conflict. Moreover, the Bay of Pigs Invasion that occurred in 1961 was an earlier failed attempt authorized by President Kennedy to overthrow Fidel Castro's government in Cuba.