Defense spending to spike $2.1 trillion under Romney

Mitt Romney is campaigning on a platform that emphasizes less spending, smaller deficits and renewed fiscal responsibility.

But in one budget area, Romney is running the opposite direction. The former Massachusetts governor wants to increase defense spending by leaps and bounds. By one estimate, additional spending would exceed $2 trillion over the next decade.

Romney's plan calls for linking the Pentagon's base budget to Gross Domestic Product, and allowing the military to spend at least $4 dollars out of every $100 the American economy produces.

With the Pentagon's base budget -- which does not include war costs -- forecast to hit 3.5% of GDP in 2013, a jump to 4% would mean an increase of around $100 billion dollars in defense spending in 2013.

The additional spending really piles up in future years.

Compared to the Pentagon's current budget, Romney's plan would lead to $2.1 trillion in additional spending over the next ten years, according to an analysis conducted for CNNMoney by Travis Sharp, a budget expert at the Center for a New American Security.

And that number assumes a gradual increase to 4% of GDP. The additional spending would hit $2.3 trillion over a decade if the Pentagon's budget were to immediately jump to 4% of GDP.

Sharp said the United States could certainly ramp up spending to meet Romney's target. But the bigger question, he said, is whether the investment would be worth the cost.

"Romney's plan might reduce military risk in some areas," Sharp said. "But you can never eliminate all the risk -- no matter how much you spend."

Romney appears willing to foot the bill. "This will not be a cost-free process," his campaign website says. "We cannot rebuild our military strength without paying for it."

Romney's plan to spend more at the Pentagon adds yet another layer of complexity to a set of proposals that would remake the fiscal landscape.

Romney has proposed a slew of tax cuts, and plans to cap federal spending at 20% of GDP. But in both cases, the Romney campaign hasn't fully explained how those provisions will be paid for.

The lack of detail means that Romney's claim of moving toward a balanced budget requires a great deal of trust.

"Romney has listed a few specific cuts he would make in discretionary spending, but they are a fraction of the extra defense spending he proposes," said Jeffrey Vanke, a senior policy analyst at the Committee for a Responsible Federal Budget.

Other budget experts expressed similar concerns about Romney's proposal, including Peter Singer, a senior fellow at the Brookings Institution, who said the plan for additional spending does not "reflect fiscal reality."

The 4% idea is not a new one. Former Secretary of Defense Robert Gates and Admiral Mike Mullen have endorsed the idea. And conservatives have occasionally used the slogan "4% for Freedom."

But some analysts questioned the wisdom of tying military spending to economic production.

"GDP rises and falls. Do you really want your defense budget falling in a recession?" said Todd Harrison, a senior fellow at the Center for Strategic and Budgetary Assessments.

"Spending should be determined by the security environment -- not the size of your economy," he suggested.

Asked if the military needs to spend 4% of GDP, Lawrence Korb, a senior fellow at the Center for American Progress who advocates for lower military spending, said "of course not."

"These artificial ways to decide the defense budget make no sense," Korb said. "And if you pursue this, how are you going to balance the budget?"

On the campaign trail, Romney frequently says that the Navy has fewer ships now than in 1917, and that the Air Force is smaller than any time since 1947. The additional funding would provide funds to bolster the fleets, Romney says.

The anecdote is largely dismissed by military experts as irrelevant, since today's Navy and Air Force are the most advanced and versatile on the planet. Non-partisan fact checkers have looked on the claim, and its associated insinuations, with scorn.

But Romney is not alone in his desire to spend more on the military. In Congress, the Republican nominee is likely to find many allies, especially conservative lawmakers from districts with military installations.

But with the wars in Iraq and Afghanistan winding down, there is an emerging coalition of liberal Democrats and Tea Party Republicans who have other priorities.

A Romney campaign official told CNNMoney that "reversing Obama-era defense cuts" is the "first step toward the 4 percent GDP benchmark."

It's true that Obama policies have slowed the rate of growth at the Pentagon. But spending on defense is still projected to grow over the next half decade.

"The Pentagon is in no danger of losing its pre-eminence under the current budget plan," Sharp said. "Romney's plan would make the military even more pre-eminent, but you can never eliminate all the risk no matter how much you spend."