UNITED NATIONS — Since the terror attacks of Sept. 11, 2001, security planners the world over have lost considerable sleep contemplating the prospect of terrorists armed with nuclear weapons. In “At the Center of the Storm,” his memoir as head of the CIA, George Tenet wrote "I am convinced that this is where [Osama bin Laden] and his operatives desperately want to go. …They understand that bombings by cars, trucks, trains and planes will get them some headlines, to be sure. But if they manage to set off a mushroom cloud, they will make history.”