The United States ended the Cold War the way a master pilot lands a fighter jet, in a sort of ecstasy of precision and the gradual reduction of force. Today, that same jet is screeching around the runway, as our capacity for messy outcomes (Iraq, Libya, Egypt) expands before our eyes. One place where the potential for unparalleled damage has increased is the US. That is because there are more tools available to terrorists, extremists or just plain kooks now than in 2001. How might a terror attack play out? Dr Andrew Krepinevich, president of the Center for Strategic and Budgetary Assessments, a non-profit research group in Washington, modeled such an attack in his book, 7 Deadly Scenarios: A Military Futurist Explores War in the 21st Century. Nuclear explosions are the main feature of his scenario for a terror attack in the US. But he foresees threats as large as nuclear attacks coming from other types of weapons. The point is not for Americans to scare themselves silly. It is to reconsider the antidotes.