The cumulative impact of the nuclear developments that occurred in 2012, from the disaster in Fukushima to Iran's continuing nuclear program, will make the world's nuclear future more uncertain. The year 2011 marked the first serious accident at a nuclear power plant in a quarter century. After the previous disaster at Chernobyl, the world’s nuclear industry axiomatically predicted that another accident—especially in an advanced country operating conventional light-water reactors—would spell the end of nuclear power everywhere. A year after three US-designed power reactors in Japan melted down in March, that hasn’t happened, but the real impact of the accident on the future of nuclear energy worldwide has yet to be felt. The accident focused attention on Japan for nearly half a year. As the threat gradually receded, the world’s focus shifted back to flashpoints where nuclear crises have been with us for a long time: Iran, North Korea, and South Asia. These weren’t resolved in 2011, and all three appear to be escalating. Two years after the United States recommitted itself to multilateral nuclear diplomacy in 2009, it became apparent that its recommitment was oversold and would not suffice to bridge serious divisions besetting Washington, Beijing, and Moscow—divisions that stand in the way of resolving nuclear crises in Iran and North Korea, or of effectively contributing to a de-escalation of an emerging nuclear arms race in South Asia.