The Fukushima Daiichi nuclear disaster gave terrorists and other malefactors a tip. By targeting nuclear plants, they can wreak havoc comparable to that wrought by an earthquake and tsunami, crippling a great economic and military power.  A terrorist version of Fukushima is plausible ― with all the human suffering, economic dislocation and national humiliation the March 2011 cataclysm entailed. Both safety and security must be enhanced at nuclear installations around the world.