The United States Military Defense budget for 2015 was in the neighborhood of $600 billion, this for a nation that has no peers, nor any other Nation-States that could possibly threaten it on any level, be it economic political or via the military. The personnel in our War Department consist of nearly 1,400,000 peoples on active duty, with another 850,000 on active reserve. Additionally, America operates or controls as reported by nationalpriorities.org, "between 700 and 800 military bases worldwide." Strange thing though, when it comes to actual war, those powers are as declared by our Constitution, held in the hands of Congress, yet, unfathomably, since WW II, America through its Congress has declared war on zero nations, yet, in the 21st century alone, America has been at war with Afghanistan, Iraq, Pakistan, Somalia, and Yemen.
All of the above clearly indicates that the military is not only a law unto itself, but pretty much does whatever the upper echelons of the military-industrial complex desires it to do. The fact is that any elected government, or unelected for that matter, in any form of State, must always, recognize that there is an implicit agreement, or explicit for that matter, between the civil in conjunction with its military arm, that they must be basically on the same page, or the military will if not given its proper tribute often exercise its power to overthrow oppressive domestic civil restraints. The thing is once any country has crossed the Rubicon, of having standing armies as a matter of course, than they have indeed set the stage at having no other choice but to stand down against such armies, or suffer the devastating consequences of military conquest within their own native country.
The crux of the matter is that it isn't good enough for the War Department to simply have all these sophisticated weapons, to have all these well trained personnel, to have all these ambitious generals, and then react to a world in which there is often strife and confusion by sitting back and doing nothing. The military can only do so many exercises, so many training missions, so many rescue missions, before there is an itching from high above, to actually do something constructive or destructive with their might. A military as big and as powerful as the United States, is akin to a superbly conditioned Heavyweight champion, who because he is the champion, is not interested in months upon months of a regimen of just training and flexing muscles, because he knows that he is far more capable than putting on a mere shadow-boxing show, instead he is there to prove himself and thereby he must fight.
The fact that our military is so big, sophisticated, talented, strong, state-of-the-art, and powerful, means for an absolute certainty, that those that push the buttons, and make the decisions, have a deeply ingrained desire to fight, and thereby that is why America is always at war, because a champion in order to be viewed as the champion, must fight and not only that he must vanquish his opponent.