I think the American bourg isn't dumb enough to think war with China would end well and hasn't figured out an exit strategy yet, but the problem is the military is getting increasingly stuffed with members of the least reality-tethered Christian subclades. Tension between the financier class and military's Dominionist moiety builds until one of two things happens: the loonies get one of theirs into the top brass and we get a bloodless coup when the president voluntarily turns the reins over to the military, or capital's contradictions build until the US finally implodes (likely because its fragile food production system collides badly with our increasingly volatile global weather patterns and causes another Dust Bowl) and we end up Mad-Maxing it while the rest of the world tries to keep us contained (option #5 fully on the table here). Regional conflicts continue to boil over and cause chaos in Eurasia in the meantime but nothing progresses to the point where we're fully embroiled in a world war.