GOP presidential nominee Mitt Romney likes to give speeches in front a big banner that reads "cut the spending." But he remains coy about what he wants to see cut, and there's one major part of the budget that he says he'd actually like to see increased significantly: defense spending.

Romney has not only not promised to cap military spending, he's consistently touted his promise to subject the military budget to a mandatory minmum equal to 4 percent of GDP, which would make the Pentagon budget 0.7 points higher than the defense spending baseline under President Obama. Where's he going to get the money for a big spending increase? The best answer is: He's probably not going to get it from anywhere.

Cato's Christopher Preble points to a Defense News article making the obvious point: Even if you can make the numbers add up, the politics don't.

Yet combined with his commitment to cut taxes and reduce the national debt, Romney’s pledge to grow the defense budget appears politically impossible, if technically doable, according to defense budget experts.

“If you put all of the promises together, it doesn’t all add up,” said Todd Harrison, a senior fellow for defense budget studies at the nonpartisan Center for Strategic and Budgetary Assessments.

“The administration may change, but the math remains the same,” Harrison said. “If you want to increase spending on defense over the next decade and reduce the deficit, then that necessarily means sharp reductions in Social Security, Medicare and Medicaid or sharp increases in taxes, or some combination of the two. But those are the major components you have to work with within the budget.”

Over the past decade, the U.S. government borrowed to increase spending, including money to fund the wars in Iraq and Afghanistan and larger base budgets at the Pentagon.

According to Preble's calculations, Romney's spending floor would require a 42 percent increase in defense spending compared to the Reagan era and a 64 percent increase over average annual budgets post Cold War. All together, the requirement would add $2.58 trillion over the next decade's current baseline. That's an even bigger challenge given Romney's other commitments. He has variously promised to cap overall government spending as a percentage of GDP, not cut Medicare, and not raise taxes. How might all of these promises fit together? Romney won't say, admitting that his budget plan can't be scored. Independent analysts that have tried to score his proposals suggest it will increase the debt over the next decade.

The 4 percent spending floor is the sort of policy gimmick that suggests that Romney doesn't take spending or budgeting seriously. He and his campaign just throw out ideas because they think it's what people want to hear. It's absurd to think that these sorts of increases in defense spending are at all necessary. And it's just as absurd to think that they're even remotely plausible given the political climate and the rest of Romney's stated policy commitments.