Fifty-five years ago this week, America dropped atomic bombs on Hiroshima and Nagasaki. So began the nuclear age.

It hasn't gone as the experts predicted. There have been no "limited" nuclear wars, and although nine nations did eventually acquire nuclear weapons, an additional 20 countries started down the nuclear path only to stop and reverse course. Today, the Nuclear Nonproliferation Treaty (NPT), the cornerstone of international efforts to prevent the spread of nuclear weapons, has more members than the United Nations.