Senior government and military officials and other experts, organized by a joint Stanford-Harvard program called the Preventive Defense Project, met behind closed doors in Washington for a day-long workshop called The Day After." The organizers of the nonpartisan project, Stanford's William Perry, a secretary of defense in the Clinton administration, and Harvard's Ashton Carter, a senior Defense Department official during the Clinton years, assumed the detonation of a bomb similar in size to the weapon that destroyed Hiroshima in World War II. A paper [they] are writing ... urges local governments and individuals to build underground bomb shelters; encourages authorities who survive to prevent evacuation of at least some of the areas attacked for three days ... and proposes suspending regulations on radiation exposure so that first responders would be able to act, even if that caused higher cancer rates. "The public at large will expect that their government had thought through this possibility and to have planned for it," Carter said in an interview. "This kind of an event would be unprecedented. We have had glimpses of something like this with Hiroshima, and glimpses with 9/11 and with Katrina. But those are only glimpses. If one bomb goes off, there are likely to be more to follow," Carter said. "This fact, that nuclear terrorism will appear as a syndrome rather than a single episode, has major consequences." It would, he added, require powerful government intervention to force people to do something many may resist -- staying put.