Or, Russia and/or China directly or via surrogates, or rogue nations, launching a surprise nuke bomb attack on the U.S. mainland?
For those who feel that that holds the greatest danger, you can check what FEMA used to think constituted a potential target for your particular state by clicking on your state name below. Be sure, though, to also read there Bruce Beach’s ‘UPDATE to Target Information!!!’ that you’ll see linked there below your state FEMA map that explains changes regarding base closings, etc., since these maps were first published in 1990. While these 20 year old FEMA maps assumed a full-out nuclear war attack from Russia and/or China, they are still instructive in illuminating how large cities and military installations are atop anyone’s target lists, even if ‘just’ a terrorist with ‘only’ a single nuke was all that’s in our future.