David Brooks writes rather bombastically that recent fiscal cliff talks prove we'll never cut Medicare enough to afford it and never raise taxes enough to pay for it, so the Obama administration is sending Chuck Hagel to the Pentagon to implement radical cuts in the defense budget.
I don't know that any of that's true, but it certainly seems like a smart plan to me. As conservatives generally point out whenever the context isn't military spending, it's very damaging to human welfare to have the government tax productive labor in order to spend money on something useless. So given that population aging is certain to lead to growing pressures on the federal budget, it's important to make up as much of the financing gap as possible by cutting spending elsewhere rather than with new taxes. And per the great Peterson Foundation chart above, the U.S. military budget is really large. Obviously, you don't want to cut the military all the way to the bone lest you invite an invasion from Mexico or Canada. But we're not even close to being overwhelmed by Canadian arms. And it's striking that if you look at non-U.S. defense spending, a majority of it appears to be by U.S. treaty allies—NATO members, Japan, Australia, South Korea, etc.—so we really do seem very safe.
Obviously, this involves some considerations outside the Moneybox framework. Maybe Mexico's military is unusually cost effective and we have no choice but to spend 50 times what Mexico spends in order to defend ourselves adequately. But from a pure budgetary point of view, this really is a strikingly large pool of money.