By Mike Mount

After spending more than $40 billion on an emergency program to save U.S. troops from roadside bomb attacks, the U.S. Army is trying to figure out what to do with tens of thousands of mine-resistant vehicles headed home from the battlefield.

The Mine Resistant Ambush Protected Vehicle program was rushed into design and production at the height of the war in Iraq as the military struggled to identify a way to protect the troops who were being killed in large numbers each day.

The hulking, heavily armored trucks, designed with a V-shaped hull to deflect the devastating effects of shrapnel and explosions from roadside bombs, played a unique and successful combat role in Iraq. But the MRAP’s extended height and extreme weight means most models can only be used in flat, open terrain or on wide roads, eliminating them from use in narrow and more rugged terrain.

Lighter, more mobile versions were designed for Afghanistan. But as the U.S. military changes its focus to emerging threats in Asia, the Army is struggling to figure out whether the MRAP can play a role in a future military where new combat vehicle programs are moving forward with new technologies.

"There are a number of people out there that are concerned with what we will do with what was a tremendous investment in MRAPS," said Col. Mark Barbosa, division chief for force development logistics, for the U.S. Army.

Army logisticians predict there will be about 20,000 MRAP variants returning from Afghanistan and Kuwait, where they have been piling up to be shipped back to the United States after service in Iraq. The Army’s plan for now is to repair and update them and put many of the MRAPS into prepositioned storage around the world for use in potential future conflicts, as well as put a smaller number in with existing support units.

With few options on the table for the MRAP, there is little or no uproar from Congress that a massive surplus of these vehicles will be sitting around for years to come - and could be potentially useless if a time comes to use them in combat theaters with different conditions than Iraq.

"The MRAP was a needed requirement to save lives and an investment was made," said one congressional official not authorized to speak on the record. "If you have them, isn’t it best to keep them on hand for now?"

But that is the problem with the MRAP: It was born and designed out of an immediate need in war and was a wild success. A lot of money was spent to protect the troops, but that leaves the military with a lot of vehicles that may never be used.

Congress is putting some pressure on the Army to determine whether there will be any role for the fleet in the future force structure. The House Armed Services Committee is asking the Department of Defense for a plan for the future of the vehicles.

The military has identified at least one role it is confident the vehicle can be used for years to come - mine clearing and explosive ordnance disposal, threats that will always endure in wars. Still others will go to train troops how to use the behemoths until troops leave Afghanistan after 2014.

But former Defense Secretary Robert Gates - the man responsible for pushing a stubborn military into designing and swiftly fielding the MRAP into the battlefield, saving hundreds if not thousands of lives - was not worried about the future.

"My attitude was, if you are in a war and kids’ lives are at stake, you’re all in," Gates said in an interview last year.

"You do whatever is necessary protect them and help them accomplish their mission, and you’ve got this stuff left over at the end, so be it…you also have left over a lot of living kids."