Basically every "made in USA" consumer product has a DOD contract. The DOD is mandated by law to purchase from US companies, so there is a huge sector of small-to-medium businesses which only exist because there is a guaranteed order coming every quarter for uniforms or boots or other equipment that would likely be 1/3 the price if they were contract-manufactured in China or Vietnam.
Not saying this is uniformly bad, because without the law the number of businesses with the ability to manufacture this stuff would trend toward zero, but it is a form of subsidy.
I wonder if this pattern is true for all militaries in rich countries. I think it sounds like good economic policy. If you want to grow your military, then you need to make sure it is spent domestically. Also, the "finish good" may include lots of parts that were built overseas. Think about a Tomohawk missile: I am sure the microchips are all made overseas. That said, the intellectual property is developed domestically (or with very close allies) and final assembly is done domestically.