Defense spending has been largely absent from the budget battle being waged in Washington despite a projected $1.6 trillion shortfall this year. Except for a handful of liberal and libertarian lawmakers, few in Congress have dared raise the possibility of reining in the military’s spending spree.

With terrorist leader Osama bin Laden killed and American combat forces preparing to withdraw from both Afghanistan and Iraq, a reduction in defense expenditures is likely in any event. Since September 11, 2001, military spending has increased by nearly 7 percent a year, up from $291 billion ten years ago to some $700 billion today.

If operations in Afghanistan and Iraq came to an end, total defense outlays would be reduced by roughly one fifth. The Pentagon would still be spending hundreds of billions of dollars on pay and benefits and housing for personnel as well as operations, maintenance and procurement though.

One of the main drivers of the department’s ballooning budget projections are mounting health-care costs. The military spent $19 billion on health care for servicemen and veterans in 2001. That is up to more than $52 billion for fiscal year 2012.

Defense secretary Robert Gates has suggested “modest increases” to the fees that soldiers and their families pay into their health-care plans. He told the Senate earlier this year that the current arrangement, “one in which fees have not increased for fifteen years, is simply unsustainable.” If it remains unchanged, “the Defense Department risks the fate of other corporate and government bureaucracies that were ultimately crippled by personnel costs — in particular, their retiree benefit packages.”

Gates also canceled or scaled down numerous expensive procurement projects, ranging from airplanes to warships which he feared came at the expense of far more important counterinsurgency capabilities. He professed more than a year ago that if his department couldn’t “figure out a way to defend the United States on half a trillion dollars a year,” its problems were “much bigger than anything that can be cured by buying a few more ships and planes.”

In what was something of a farewell address last March, Gates laid out his vision on the future of the American military, professing that “in the competition for tight defense dollars within and between the services,” the focus should be on preparing for naval and air engagements.

The prospects for another “head on clash of large mechanized land armies seem less likely,” he explained, so the Army and Marine Corps will be challenged to maintain their high troop levels once the American involvement in Afghanistan and Iraq winds down.

When Gates took office in 2006, in order to “relieve the severe stress on the force from the Iraq war as the surge was getting underway,” he expanded the Army by some 65,000 troops, bringing it up to a total of 547,000. 27,000 troops were added to the Marine Corps which currently employs more than 200,000 men and women. Gates later added another 22,000 troops to the Army.

Starting in 2014 however, when NATO intends to transition security responsibility to Afghan forces, Gates proposes that the military begin reducing the active duty Army by 27,000 and the Marine Corps by between 15- and 20,000.

“The strategic rationale for swift moving expeditionary forces” remains self-evident, according to Gates, “given the likelihood of counterterrorism, rapid reaction, disaster response or stability or security force assistance missions.” Like his predecessor Donald Rumsfeld, he wants a more flexible and agile infantry — a “leaner and meaner” force.

Gates has already identified some $400 billion in unnecessary defense spending over the next decade but warned last year that “tough economic times or the winding down of a military campaign” should not lead to “steep and unwise reductions in defense.” It will be up to his successor, current intelligence director Leon Panetta to argue that steeper spending reductions may not in fact be unwise at all.