Anyway, to the OP's question... We shouldn't reduce military spending because 1) it's not actually that much compared to all the other things we spend our money on and 2) Pax Americana
Y'all may not much like it, but US military might is the single largest reason that there has been as little global armed conflict as there has been in the last 70+ years. The US hasn't been imperialistic since the late 19th century, we've only annexed territories that wanted to be annexed, and for the last century, we've been pretty damned happy to just hold our own - and support our allies. And while it might chafe some of you... pretty much all of Europe and our fellow English-speaking countries are dependent on US military firepower to maintain their own borders. Hell, there are a fair number of Asian countries that benefit from our presence throughout the globe. If it weren't for active military patrols and bases throughout the world, both China and Russia would be much much bigger than they are now.
It sucks, but pretty much if the US materially cuts military spending, China and Russia will start gobbling up their neighbors, NK will start shit with their southern neighbor, and the middle east and the indian subcontinent are going to be a mess.