The overwhelming majority of U.S. military equipment is made in the U.S. That includes clothing and footwear.
The U.S. textile industry makes the world’s most advanced polymers and fibers.
The U.S. is also a leader in technologically advanced clothing that includes body temperature control, perspiration reduction, injury treatment, waterproofing, and bacteria blocking.
As for China, it’s industrial prowess is fading fast. Factories are closing more than opening and it is losing manufacturing jobs faster than gaining them.
That is good, though if some cannot compete then they scam:
Wholesaler Took $20 million from U.S. military for Uniforms, Gave it Chinese Knockoffs including counter-night vision clothing that didn’t actually work
The procurement violated the Berry Amendment and Trade Agreements Act, which mandated that goods be made in the U.S. and a select number of allied countries, with China obviously not on that list.