The Cubans and Soviets began secretly establishing sites to launch nuclear missiles from Cuba. With the use of these missile bases, the Soviet Union could have first strike capability against the United States.
The United States discovered the existence of these missiles. President John F. Kennedy and his advosers considered several different strategies ranging from diplomacy to a blockade or even a full-scale invasion of Cuba.
President Kennedy eventually chose a blockade. The U.S. Navy placed ships in the Carebbean Sea surrounding Cuba and would not allow any Soviet ships to reach Cuba.
Kennedy announced the threat to the nation causing panic and turmoil across the country. Throughout the next several days, the crisis continued to escalate as both sides refused to back down.
1962.10.22+ The United States insisted ⪢⪢
that the missile bases be removed while the Soviet Union and Cuba refused to admit that the bases even existed. As the days continued, the Soviet Union remained diligent and the Kennedy administration began preparing the early stages of an invasion plan.
On October 25th, the blockade was challenged for the first time. Soviet ships approached the quarantine zone but American ships held their ground. The Soviet vessels were forced to turn back and the blockade continued.
On that same day, the US embassadar to the United Nations, Adlai Stevenson, confronted the Soviets in the UN assembly revealing photographic evidence that forced the Soviet Union to admit the missile bases existed.