What event during the Kennedy administration nearly led to world war?

The event during the Kennedy administration that nearly led to World War III was the Cuban Missile Crisis in October 1962. The United States discovered Soviet nuclear missiles stationed in Cuba, just 90 miles from its shores, prompting a tense 13-day standoff between the U.S. and the Soviet Union. President Kennedy imposed a naval blockade and demanded the removal of the missiles, leading to heightened tensions and fears of nuclear conflict. Ultimately, a diplomatic resolution was reached when the U.S. agreed to remove its missiles from Turkey in exchange for the withdrawal of Soviet missiles from Cuba.