My conflicting views of a downsized military

So, Sec. Def. Chuck Hagel says the US military needs draw down to force levels similar to that of WWII....or around 450,000 troops. Basically the US will still be able to defeat any adversary on Earth, but would not be able to spend protracted time occupying other countries the way we have in Iraq and Afghanistan. There's just no money in the budget for it. 

As ex-military, I used to be a war hawk on this stuff, but as a libertarian I think we need to let other countries solve their own problems or suffer with them, whichever, unless the danger there poses a clear and present danger to the US. Neither Iraq, Afghanistan, Libya, Bosnia, etc. represented immediate threats and we can't afford the blood or treasure to police their countries for political or even humanitarian reasons, or to put it cynically, to create a reason to prop up American defense contractors.

I realize China and Russia are building up their war machines, but are we still the sole check on communist expansion, if that's what they have in mind, in the modern world? Are we prepared to go to war with China over Taiwan or Russia over the Ukraine? Have we ever been? That's likely world war you're talking about....and I don't think the Russians or Chinese want that any more than we do. They know we'll eventually defeat ourselves economically and they'll have won without firing a shot. 

I do question why Hagel is cutting pay and benefits for the troops, but I saw no mention of downsizing plans for Pentagon staffing. That's probably because most of the troops vote R while the ass-kissers in the Pentagon have learned which side their bread is buttered on and dutifully vote D as long as Obama is in charge. I'm sure the bureaucracy at the Pentagon will end up like the education bureaucracy, bloated and top heavy with expensive administration and very little usefulness on the battlefield.