Former Speaker of the House Tip O'Neill famously remarked, "All politics is local."

The same holds true for nuclear terrorism.

The recently released Planning Guidance for Response to a Nuclear Detonation, developed by the White House Homeland Security Council, stresses that it's "incumbent upon all levels of government" to prepare "through focused nuclear attack response planning." Mayors, governors, emergency managers and first responders will be the first to deal with the consequences, and according to that same guidance, "local and state community preparedness to respond to a nuclear detonation could result in life-saving on the order of tens of thousands of lives."

Ready or Not?, a yearly analysis of preparedness for health emergencies that's released by the nonprofit Trust for America's Health, found that "surge capacity remains the largest threat to the nation's ability to respond to a major catastrophe." Local, and specifically, regional abilities to care for the wounded will be vital just after a nuclear terrorist attack. Unfortunately many communities haven't gotten the point.

Two assumptions prevail at the local level: 1.) Any nuclear explosion will completely destroy a major city; and 2.) The military is the only organization capable of responding.

These ideas are fueled by Cold War-era memories in which the threat of nuclear war with the Soviet Union meant thousands of bombs would fall on U.S. cities. However, scenarios involving a nuclear terrorist attack, though horrible beyond comprehension, are not in the same league.

Undoubtedly the federal government would eventually take charge of response efforts and military aid would be required. Yet as overwhelming as it would be for local and state resources, they would be all that's available in the first hours and days following an explosion.

So what should local officials do?

First, come to grips with the threat and understand that the military can't arrive immediately to help. Though there's a low probability of such an attack compared to conventional explosives, natural disasters or bioterrorism, the possibility is real and the consequences are catastrophic. Most importantly, local officials shouldn't delude themselves by thinking that existing response plans to "dirty bombs" can be simply ramped up to deal with nuclear terrorism -- there's no comparison between the two. As Harvard professor and nuclear terrorism expert Graham Allison describes it, "a dirty bomb is to a nuclear bomb as a lightning bug is to lightning."

When this lightning strikes, it may be several days before the federal government can respond in force. Although the Defense Department has recently tasked thousands of U.S. troops to support local authorities in case of such a catastrophic event, local officials should assume substantial federal help might not arrive for up to 72 hours after the explosion.

Second, realize this isn't a problem for only large, high-risk cities, but one that requires a regional response. Though an entire targeted city wouldn't be destroyed, surrounding communities and states would be called upon for aid. People would self-evacuate and find themselves miles away by the end of the day, fallout would be blown long distances, and the only resources available would be found in surrounding areas.

Third, make actual plans. This must take place across local borders and among disciplines that often compete for scarce resources -- and should include businesses and other private entities that often aren't invited to the table. As recommended by the recent Weapons of Mass Destruction Commission, a serious program of engagement with the public will be required to not only encourage disaster preparedness, but provide guidelines so that they can track their local officials' progress.

Truly comprehensive plans at the regional level then must be connected with their federal equivalents. If officials can't coordinate their efforts, all this work could become counterproductive.

Such preparation isn't necessarily specific to nuclear terrorism. Regional preparedness and response can be used for a range of catastrophic events, including hurricanes such as Katrina. Moving down the scale, preparing for the "big one" will help communities deal with the small disasters they face every year.

Arnold Bogis is a fellow at the Belfer Center for Science and International Affairs in the John F. Kennedy School of Government at Harvard University.