The Americans haven't become that deranged—yet.

Additionally, I doubt that the US will ever engage in a shooting war with a major, nuclear-armed power. Most likely, the US will try to turn Asia-Pacific countries into another Ukraine and have them fight China for it.

Edit: If that fails, then the US will either relinquish its' neoliberal hegemony and continue the path of industrialization and modernization or it will blanket the world in nuclear fire.