A common trope of hawkish foreign policy writers is that America took a "holiday from history" by starting too few wars and trimming military spending in the 1990s. The unsubtle suggestion is that this holiday caused 9/11. But a better analogy would be that America, for decades, has taken a holiday from arithmetic, spending money like Jill Kelley at a JSOC mixer.
America is so comparatively wealthy that it has spent roughly what the entire rest of the world spent on defense for 20 years. Even this figure is somewhat misleading, since if you include the spending of our allies and partners across the world—whom one presumes we're not preparing to fight wars against—we currently spend between two-thirds and three-fourths of world military spending.
Only the recent fiscal crunch, caused by ballooning government spending (including defense), relatively low taxes, and an economic collapse, made us consider trimming our sails a little. Not much, though: Even if sequestration happens, which seems unlikely, military spending would wind up at 2007 levels in 2013—2007 was hardly a lean year at the Pentagon.
But for the proponents of lavish Pentagon spending, the prospect of a haircut looks more like a beheading. Robert Kagan warns in the Washington Post that if the sequester happens, the "preservation of the world order" is in doubt. When you dig into the basis for this argument, though, it's not persuasive.
Kagan and his confreres offer a number of arguments for why a less interventionist America would produce global chaos, but fortunately none of them are persuasive. The "world order" the foreign-policy community frets about is hardly as fragile as they think: No country has the ability to reverse international trade militarily, it's not clear which of them would even want to, and the costs to the United States of conflicts between third parties have been overstated. It's odd to hear the proponents of the status quo congratulate themselves for supporting a system that benefits all countries and in the same breath suggest that the beneficiaries of this system would try to blow it up.
Similarly, small, weak states rarely pose serious threats to U.S. security, so we don't need to try to run them better ourselves with the U.S. military. Moreover, there is no taste among the American public for making the Syrian civil war an American war, and there is considerable skepticism about buying an Iran war from the crowd who sold us Iraq and Afghanistan.
Finally, our global military presence inhibits friendly countries from doing more to defend themselves. These countries view us as Uncle Sucker, a powerful but dimwitted dupe who is all too willing to spend his own money on their defense while they spend their money on domestic priorities. American taxpayers aren't just asked to support a bloated welfare state at home, they're asked to fund free riders in foreign welfare states, too. Enough.
A better question than whether the Kaganites are correct about the threats we face is what it would take to cause a rethinking among American strategists. The sequester has identified fiscal constraints as one, but America remains so rich and powerful that it probably can continue throwing good money after bad on a strategy that has long since outlived the conditions that produced it.
Thucydides wrote that "the strong do what they can and the weak suffer what they must." But being so strong as to be insulated from costs and benefits can lead to a condition about which the Greeks also taught us: hubris. In all likelihood, America will continue to have a wild and crazy grand strategy that spends our blood and treasure prolifically and unnecessarily for one major reason: because we can.