In his recent budget announcement, President Obama staked out a negotiating position with Congressional Republicans by offering a sense of symmetry: a 7% increase in the military budget to balance out a 7% increase in domestic expenditure.

Characteristically, the Republican leadership pronounced the President’s draft proposal dead on arrival. And so began the months of wrangling and posturing.

Much of of this infighting will be lost on the American public. Nothing, after all, could be duller than debating numbers. And yet it matters. As Aaron Widalsky, one of the leading scholars of the budget put it, “you can see who ‘won’ and who ‘lost’ by studying ‘who got what.’”

So let’s take a closer look at the numbers.

The fact that the President wants to spend more money to introduce new domestic programs, like free community colleges, is fairly easily explained. Freed from the shackles of reelection, we get to see what Obama cares about. The term “middle class economics” may lack the poetry of some of his predecessors’ initiatives but it is catchy enough to fit a sound bite. And who wouldn’t want to leave behind a legacy of free community college education, however unlikely it is to happen?

No, the real puzzle is the 7% increase in military expenditure.

Now it is true that any Republican who vocally resists supporting this increase risks alienating the party’s base.

But no serious negotiator would encourage the president to offer such a carrot. Strategically it would make better sense to let the Republicans ask for it. So what is happening here?

The Pentagon already has a big budget

A lot has been written about the size and growth of the military budget over the last few years. And there are many numbers to include - or exclude.

To start with there is the Pentagon base budget; then there’s the additional budget that is used for fighting wars known as Overseas Contingency Operations; and there are also the budgets of associated agencies, such as Homeland Security or the Coast Guard. The net effect is what many politicians and pundits intend – to cloud our understanding and thus our judgment.

But here is what remains crystal clear: America still outspends the next 18 countries of the world combined.

The highly respected Stockholm International Peace Research Institute says the US spends nearly four percent of its GDP on the official military budget. That is over three times what is spent by the next largest country, China.

The war in Iraq and Syria against the Islamic State is a relatively recent additional expense. Gordon Adams, a noted expert on defense budgets has estimated it could cost over $10 billion in 2015 alone. But this is small number in comparison with the expense of the military presence in Iraq and Afghanistan for over a decade. These, Adams suggests, added about $1.5 trillion in military costs to the federal debt between 2001 and 2014.

But Obama ended the wars in Afghanistan and Iraq

Here is the puzzle: In every other era in US history the cessation of full-scale war has been followed by a reduction in the scale and cost of our armed services.

In the 1990s, at the end of the Cold War, the effect was dramatic with an estimated cut in the region of 45 percent.

So, even allowing for the fact that the US is still involved in a partial war in Iraq, why would a president who avowed to wind down two wars advocate increased defense spending?

There are several possible answers.

Why increase military spending?

One popular one offered by Obama’s critics is that the president has no plan and is therefore driven by current events. These include the renewed need to shore up NATO’s defenses against Russia in Europe; the continued “rebalancing to Asia;” America’s emergent, and potentially expensive Arctic policy; and, of course, the continued struggle against Jihadist militancy in the Middle East and North Africa.

I have already mentioned a second explanation: that it is a bargaining strategy to get what the President really wants, albeit a rather strange one.

The real answer for the request for 7% increase, however, lies outside the orbit of simple parochial Washington politics and has far more to do with how America sees its role in the world.

President Obama, in the tradition of his predecessors dating back for several decades, considers the US to have an indispensible role as a global “stabilizer.”

According to this view, the chaos we witness would be far worse in the absence of America’s abiding commitment to patrol the Straits of Hormuz, the South China Sea and the Arctic Sea. It would be exacerbated without its flights over Syria, or its troop deployments at an estimated over-600 military installations or bases around the globe.

The logic for an enhanced military budget is compelling: America’s security and prosperity are linked to a stable world in which global free-trade flourishes. This is the logic that has dominated US strategy since the end of World War II.

But that policy is expensive – and we have seen reductions in the past that defy that logic. So it leads to the inevitable question: how much do we need to spend to achieve these goals?

How much is enough?

Since the turn-of-the-century, the answer has been that no sum is sufficient.

The rumor mill suggests that, all told, we could spend $1 trillion on various defense services this year. The military services justify this level of expenditure because they believe that you can’t put a price on security.

They need, they say, to plan years, even decades ahead in terms of their boats, planes and munitions. They understandably get frustrated by the Washington wrangling and each branch of the service pushes for what they regard as essential new tools.

But the question remains: when is enough in fact “enough”?

As the candidates begin jostling for position in the 2016 presidential election, they will offer a variety of answers.

Elements in the Republican party, represented by people like Rand Paul, argue that it is time to reduce our overseas commitments and with it our budget. Other Republicans have been more circumspect in offering an opinion at this point. Democratic frontrunner Hillary Rodham Clinton, has – in contrast – left nobody in any doubt that she would support a muscular foreign policy and, with it, presumably retain a bloated military budget.

Regardless of their current positions, the example of President Obama is sobering.

He was an avowed candidate in favor of a wind down in the military budget who evolved in the job into a seasoned president in favor of its increase to historic levels.

Truly, if it could happen to him, it could happen to them all. Clearly, as they used to say, the job makes the (wo)man.