A war over Taiwan is likely to be long, not short; regional, not localized; and far more easily started than ended. It would expand and escalate as both countries look for paths to victory in a conflict they feel they cannot afford to lose. It would present severe war-termination dilemmas and involve far higher risks of going nuclear than many Americans realize. If Washington doesn’t start preparing to wage, and then end, a protracted conflict now, it could face catastrophe once the shooting starts.