sentences:  Modern tactical nuclear warheads have yields up to the tens of kilotons or potentially hundreds several times that of those used in the atomic bombings of Hiroshima and Nagasaki.Strategic thinking under the Eisenhower administration and Secretary of State John Foster Dulles was that of massive retaliation in the face of the Soviet Union's nuclear arsenal.Meanwhile, many of the most destructive deployed thermonuclear weapons were developed by both superpowers.