The main issue here is that our entire airforce, most of our submarine force, our entire air refuling wing, over half of our cargo aircraft, a good portion of our assault rifle inventory, and about 1/3rd of our navy are all reaching end of usable hardware life. Airplanes in particular can only fly so many hours before you either have to completely rebuild the structural components including the wing spars and fusalage. Ships that don't get adequatly maintained, rust out and sink.
Is there bloat in the military? certanly. but there is also a huge amount of money spent on maintaining obsolete equipment. Building an entire new fleet of F-22's and scrapping all the F-15's would literally be cheaper than maintaining our existing fleet. or hell, building an entire new fleet of F-15's. We lie to ourselves and say "Oh, the F-22 is sooo much more combat effective than the F-15, that each one of those aircraft counts as 20 of the old style!" except that when you lose one of those, you also lose the equivelent of 20 aircraft. Very soon, we aren't going to have the capacity to move men and materials to foreign countries. We won't be able to support refueling efforts. We won't be able to replenish ships at sea. These capabilities are critical. Abandoning them leaves is vulnerable.
Our nuclear deterrent is being reduced steadily as well. Our current president has made it a mission to eliminate nuclear weapons wherever possible, primarily from our own arsenel. At the same time, China is dramaically expanding their launch capabilities, building up their military, particularily in the form of a navy, airforce and nuclear balistic missile equipped submarine forces.
At the same time, you have our southeast asia foreign policy. Australia, Thailand, Sri lanka, South Korea, Taiwan. These countries should sound familiar to you, because they are the countries that follow the words "Made in" on the bottom of most of your electronic devices. Well the ones that aren't made in china already for the most part. China means to exert economic control over this area of the planet. This same area of the planet where a single flood managed to wipe out 70% of the hard drive production capability on the planet. Sure, positive change in foreign policy is great and all. Negitive change in that region with our economy in the fragile state it is in, would absolutly destroy us right now.
We have a large military than most. We have an even larger area of control to protect than most. The national guard is underequipped. Our domestic interceptor fleets are too small to effectivly repell an invasion, but they didn't have to be because we have a credible nuclear deterrent. Soon, we won't. Nuclear bombs are useless if you cannot deliver them to target. our nuclear ICBM fleets have been reduced to 450 missiles, with more reductions possible given the current administration. Most of those warheads are smaller "tactical" nuclear warheads. Our ohio balistic missile submarines have had their missile complements halved by treaty, and the older boats are due for replacement with no replacement in sight.
So yes, if we were to cut our current military spending in half, I believe we would be in danger. I believe china would sieze on that oppertunity, and we wouldn't be able to do sh*t about it without resorting to nuclear options. If we were not facing the huge wall of aircraft about to hit mandatory retirement age in the next 10 years, it might be a different story. if we had replaced those on the schedule they were supposed to be replaced, it would be another story. If china wasn't building out their military at a high rate of speed, it would be another story. But this is the one we are playing out.
The fact that a relitivly benign superpower exists in the world prevents more wars than it causes. The tiny conflicts we call "war" these days are nothing compared to the conflicts of the past. And every single conflict of the past was caused by people who cut spending too far and left themselves open while others built.
You can wish for "Peace in our time" all you want, but it doesn't mean the germans aren't going to invade Poland anyways...