The West is unprepared for everything all at once.
Cruise missiles explode sleeping American servicemen in Guam, Japan, and the Mariana Islands. Fifth generation fighter jets shoot scrambling American pilots from the sky, competing meaningfully for air superiority for the first time in a century. American submarines are sunk as they struggle to slow, then fail to stop, a naval armada that is as big or bigger than the one that liberated Europe.
The invasion of Taiwan has started, and the eyes of the world are less upon the United States than upon a suddenly terrifying China. To keep it that way, and to show they really mean business, as if the hypersonic missile strikes on Alaska and Hawaii were not enough, Beijing conducts “a nuclear test” somewhere over the Eastern Pacific. The mushroom cloud can be seen from California.