a) Anything China produces, the US can produce (with a modicum of effort). The reverse is not true (see jet engines);
b) China is profoundly dependent on sea lanes for food, fuel, and the exports that drive its economy.
The US is the only major industrialized power that is nearly resource independent, and its economy does not depend on exports, and only to some degree on imports that can be sourced elsewhere if necessary.
In a war scenario, China could inflict a lot of damage on US naval forces close to shore, but China would be blockaded, and the rail routes through Central Asia and Siberia are too puny to carry the weight of Chinese exports and imports.
Plus all those Chinese dollar-denominated accounts would immediately become illiquid, as the US would refuse to clear any transactions involving Chinese banks and would severely penalize any third party trying to do so on China's behalf (Europe).
If push comes to shove with the US any time in the near future, China is screwed.
Autarky | Definition of Autarky by Merriam-Webster
https://www.merriam-webster.com/dictionary/autarky
Autarky definition is - self-sufficiency, independence; specifically : national economic self-sufficiency and independence.
Thanks to fracking, we have reached the stage of near-Autarky; sure we import lots of stuff, but in contrast to China, do we absolutely have to? I would point only to rare earths. China seems to have an export monopoly,yet we have an island loaded with the stuff in southern Alaska that only the fanatical environmentalists keep us from mining.