I don't think you understand the premise. China cannot force payment. The US is doing it because they want the dollar to stay high. It's pretty adorable that you think just not paying is a thing to any country. That's been done: Greece, Zimbabwe, China in the 90s and it keeps turning out the same way.

China isn't paying because they can't afford to. Stealing isn't a flex, buying a supercar is though (NGAD, Patriot missile system, worlds largest car carrier fleet, worlds largest and most numerous ballistic missile subs, etc).