"PARIS — Cuban leader Fidel Castro asked the Soviet Union in 1962 to launch a nuclear attack on the United States if it invaded Cuba, according to letters published today by a French newspaper.

The respected daily Le Monde said the letters were exchanged between Castro and Soviet leader Nikita S. Khrushchev during the Cuban missile crisis.

In an acrimonious reply, Khrushchev suggested that Castro was irresponsible, since such a war would have killed millions of people in both East and West and destroyed Cuba."