Legitimate question, always a good thing to start with.  

I've never favored the world police role for our country.   On the flip side, it gave us power and a negotiating tool being the unquestioned leader of a dominant military.       Sure, Japan can build a new fleet, Europe can arm themselves, add to the nuclear weapons.  We'll be putting small nukes in the hands of the Saudis soon I expect, at best we're giving them a ton of military hardware to help control that area of the world (even if they don't have American interest in mind 5 years from now)

Here's another question.   Is the world a safer place with America as the dominant military or, do we let the worlds regions chose their own alliance separate from the U.S.        It's a legitimate question, what are the risk/rewards of losing control of military conflicts internationally?