When, in 1997, the International Atomic Energy Agency unanimously elected Mohamed ElBaradei as its next Director General, few observers could have forecast the dramatic role he would play over the next 12 years. Certainly, the stage onto which Dr. ElBaradei stepped—featuring Saddam Hussein’s Iraq, Kim Jong-Il’s North Korea, Muammar al-Gaddafi’s Libya, and the Islamic Republic of Iran—gave ample...