I'd like to suggest another reason for large military expenditures that have nothing to do with corruption. The US has the only two-ocean navy, and a very extensive one at that. A lot of the burden of protecting shipping lanes for members of the "global system" is covered by the States. That's really, really expensive.
Of course, that means that countries that don't want to play by US rules (North Korea, Iran, Cuba) get shafted, but it's still a better explanation of the crazy military costs than either fear or corruption.