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.