U.S. President John F. Kennedy and Soviet Chairman Nikita S. Khrushchev were deeply sobered by the near catastrophe of the October 1962 Cuban missile crisis. Each knew that the U.S. and Soviet Union had stumbled into a crisis that could easily have exploded into a war that destroyed human civilization. On the heels of the crisis, Khrushchev said he looked forward to "six more years" of working with, rather than against, JFK. But on 22 November 1963, Kennedy was assassinated. And in October 1964, Khrushchev was removed in a coup. Their successors were unable or unwilling to sustain the positive momentum and the Cold War reasserted itself all over the world.For a half-century, many have wondered: what might the two leaders have accomplished? Here are some of the most tantalizing what-ifs of the entire 20th century: if JFK had survived Dallas; if he had been reelected in November 1964; if he had remained healthy enough to serve out the second term through January 20 1969; and if Soviet leader Nikita Khrushchev had avoided the coup that removed him in October 1964—if these conditions had been met, what might JFK and Khrushchev have accomplished in matters of war and peace? Might they have ended the Cold War then and there? Might they have begun to move to abolish nuclear weapons at a pace that would have produced a non-nuclear world by now? Might the catastrophic Vietnam War been avoided? Might the U.S. and Cuba have achieved rapprochement? And what are the lessons for today's leaders from both the history that did happen, and that which might have happened?