As the insurgency has matured in Iraq, so has its ability to piece together extremely powerful bombs that no amount of additional armor plating can stop without overtaxing the standard chassis, officials told the House Armed Services Committee. Humvees have been loaded with as much armor as they can carry.

"We are at the 98-percent point. We can't put any more armor on these things," said Marine Brig. Gen. William Catto, director of Marine Corps Systems Command, in testimony to the House Armed Services Committee. "My opinion is we are going to have to design a new class of vehicle from the wheels up."

About 70 percent of the injuries and deaths to U.S. military personnel in Iraq are the result of improvised explosive devices, according to Lt. Gen. James Conway, the director of operations.

But just adding armor to vehicles and troops can actually hinder them on their mission.

"Eventually you get to the point where the lack of observation (from too much armor) has the opposite effect," said Lt. Gen. James Mattis, commander of Marine Corps Combat Development Command. Troops on the road find more than half of IEDs before they explode, primarily though keeping sharp watch and using high-powered sniper scopes to check suspicious bundles.

The Army has begun building a new Humvee -- the 1151 model -- to find the balance between added armor and performance. That tactical vehicle will build armor into the chassis and base plate, leaving off the armored doors and some steel plating. The doors can be applied when the vehicle moves into a dangerous deployment, like Baghdad. But the vehicle can operate without them at higher speeds and with more maneuverability.

The Army has ordered more than 1,500 of the newly designed Humvees and will begin testing them in the next few months.

The current generation of up-armored Humvees cannot be lightened to move with ease at high speeds, one of the techniques employed in Iraq to reduce exposure of personnel to IEDs.

"They get bogged down" in the sand, said Army acquisition executive Brig. Gen. Jeffrey Sorenson, referring to the up-armored Humvees now required for use across Iraq and Afghanistan. "That's why we were reluctant to use them right away" in Iraq, in the early days of the occupation before the IED threat manifested in the fall of 2003.

At that point the requirement for armored Humvees took off, climbing from around 200 to more than 8,000, almost entirely comprised of add-on kits that can be affixed to the vehicles in the field. The requirement for add-on kits is now well more than 13,000.

The Marine Corps is also making available to commanders who request it underbody protection kits that provide extra protection from land mines or bombs left on the road. The standard add-on kits don't provide undercarriage protection, and there has been an increase in IEDs.

Up-armored Humvees are manufactured from the start to have thick ballistic glass and fully armored doors. There are some 8,000 in Iraq and Afghanistan, and the requirement continues to grow. Only one company, Armor Holdings, produces the armor used on the vehicle, a situation that keeps production down to around 550 a month, the generals said.

The military also uses a large number of standard Humvees that are plated after the fact with strap-on armor and often jerry-rigged in the field with additional protection like mesh netting and sand bags by troops.

The Marine Corps is in the process of upgrading nearly 7,300 Humvees with the most advanced armored kits -- just 12 percent of them are installed. It will also buy 498 manufactured up-armored Humvees of its own to be delivered from June to September. The Marine Corps has been primarily relying on up-armored Humvees borrowed from the other services for duty in Iraq.

The Marine Corps is in the beginning stages of thinking about an entirely new vehicle that will combine both speed and protection for troops conducting stabilization operations like those in Iraq and Afghanistan, Catto told United Press International.

For its part, the Army is developing an experimental vehicle known as the Future Transport System, Sorenson said, which is expected to yield a prototype in 2007.

Lawrence Livermore National Laboratories has developed an armor kit for 5-ton trucks, which regularly ply the roads of Iraq carrying troops and supplies and have had, historically, the least amount of armor protection.

The new "Gun Truck" is based on the version used in the Vietnam War, according to Steve DeTeresa of Lawrence Livermore. It is designed to help armored Humvees protect convoys. The sides are armored with steel plates left over from the Stryker Combat Vehicle production line and topped with ballistic glass. The truck carries multiple machine guns that can repel simultaneous attacks from multiple directions.

The armor protection and the firepower far exceed the up-armored Humvee with its single machine gunner. There are just 31 built and deployed to Iraq. Each kit to turn a standard 5-ton truck into a Gun Truck costs about $40,000.

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