This is not necessarily some petro-dollar argument. Individuals in other countries and their central banks want to save or hold USD in reserve for a variety of

This is not necessarily some petro-dollar argument. Individuals in other countries and their central banks want to save or hold USD in reserve for a variety of reasons (local currency inflation, exchange rates, etc). They buy dollar denominated bonds. This essentially allows the US massive access to credit which can fund these sorts of ventures. I can make the same argument without mentioning the military - we benefit from a virtuous cycle of having the most dynamic economy which allows us access to credit to improve it, making it even more dynamic, and we simply pay it back as a lesser share of % GDP later.