Predators know to hunt the weakest animal in the herd. So do the Iraqi insurgents. It is an essential truth about the Iraq war that's ingrained in soldiers like Pvt. Daniel Rocco, a Humvee gunner with the Second Battalion of the 82nd Field Artillery Regiment. Rocco's unit is an artillery regiment trained for conventional warfare, not escorting convoys. But the "Steel Dragons" of the Second now spend most of their days protecting the weak: VIP visitors and 18-wheel trucks loaded with food or other supplies on the road to Baghdad. In the process Rocco's unit gets hit regularly with small-arms fire, improvised explosive devices (IEDs) and even suicide car bombs. He displays reddish pockmarks and scar tissue up his right arm, the effects of an IED from last May. "I really can't close my right hand," he says. And Rocco's Humvee is, today, equipped--with "Gypsy racks"--steel-plated cages around the gunner--and other add-on, improvised hardware, known as "hillbilly armor." "It's Mel Gibson 'Road Warrior' stuff," says Capt. John Pinter, the battalion's maintenance officer. "We're not shooting for pretty over here."

This is the ugly reality that National Guard Spc. Thomas Wilson was apparently trying to convey to Donald Rumsfeld in Kuwait last week. There is no front line in Iraq. Or, to be more precise, the front line is wherever the insurgents decide it is. And very often they decide it should be trucks and unarmored Humvees at the back of supply lines--what used to be known, in other wars, as the rear area. Because the insurgents present a 360-degree threat, the most vulnerable units are often the ones the Army pays the least attention to: poorly equipped National Guardsmen or reservists in supply and transport companies. During a Q&A while the Defense secretary was stopping off in Kuwait, Wilson asked Rumsfeld: "Why do we soldiers have to dig through local landfills for pieces of scrap metal and compromised ballistic glass to up-armor our vehicles?"

Rumsfeld's initial response was testy. "You go to war with the army you have," he barked. Wilson's question, it turned out, had been planted by a reporter embedded with Wilson's 278th Regimental Combat Team, which was about to head into Iraq in a long convoy of unarmored vehicles. But Wilson's brave words brought applause and shouts of approval from the other 2,300 soldiers in the hangar at a base in Kuwait.

His question is still resonating. Many critics on both sides of the political aisle are asking whether the Pentagon is adjusting well to the insurgents' tactics. Is Rumsfeld, in other words, fixing vulnerabilities as quickly as the Iraqi insurgents spot them? President Bush reassured Americans last week that "we're doing everything we possibly can to protect your loved ones in a mission which is vital and important." But as the death toll climbs to nearly 1,300, some soldiers and defense-industry officials insist that much more could be done. Eighteen months after Bush declared that "major combat operations" in Iraq were over--and another war began--the most powerful military machine on the planet, replenished by America's unmatched industrial power, is still sending its soldiers, reservists and National Guardsmen down dangerous roads in soft-skinned trucks and Humvees.

Humvee factories, meanwhile, have not been operating at full capacity. And U.S. commercial steel-plate companies have been largely ignored by the Pentagon, which remains intent on supplying itself from a select number of Army depots. Perhaps inadvertently, the Pentagon late last week provided proof that it had not been doing its utmost. Two days after Rumsfeld's embarrassing exchange with Wilson, the Defense Department announced it was ordering 100 more up-armored Humvees a month from their main supplier, O'Gara-Hess & Eisenhardt in West Chester, Ohio. The Humvee armoring company had told reporters only a few days before that it was operating at 22 percent under capacity, but that there were no more orders from the Pentagon. Then suddenly there were more, for reasons the Army did not make clear. (The Pentagon claims it did not know about the additional capacity until the head of O'Gara's holding company, Armor Holdings of Jacksonville, Fla., announced last week that it was possible.) The new Pentagon order boosts production from 450 to 550 up-armored Humvees a month, neatly filling in O'Gara's capacity gap.

Every little bit of additional production will help. Of the 19,782 Humvees currently in the Iraq theater, according to the Army's latest numbers, only a little more than a quarter, or 5,910, are the new M-1114 model, which is armored top to bottom and can withstand the weight because it has an improved transmission, a 6.5-liter turbo diesel engine and a tougher chassis. An additional 4,737 Humvees have no armor, and most of the rest have been modified with add-on kits. The problem is that these add-on Humvees sometimes break down under the weight or move too slowly in dangerous situations. "The modified armor makes vehicles slog," explains Pinter. And do-it-yourself hillbilly armor sometimes makes the vehicles less safe, especially when exposed to bombs. Why? Because poor-quality steel can turn into shrapnel.

There are no firm figures on how many soldiers have died or suffered grievous wounds because of lack of armor. But even during the recent Fallujah offensive, several Marine infantry units rolled into battle with soft-skinned and open-backed Humvees. Many of the Marines grumbled that all the armor was being sent over to the Army. But some Army troops wouldn't agree: in October, members of one unarmored unit, the 343rd Quartermaster Company, refused to carry out a convoy mission because their vehicles were not adequately protected. Several members were later disciplined and demoted, though the Army declined to court-martial them. In a recent letter to the Army Times, Sgt. Scott Montgomery, who was part of a different unit that eventually did carry out the mission, said his convey was hit by an IED and that he was wounded by shrapnel. "Had we not had armor on our vehicle, my entire crew would have been killed," he said.

Rumsfeld arrived at the Pentagon determined to overhaul an antiquated Army, making it smaller, faster, lighter, but every bit as lethal. He succeeded, at least in the early going. Following the "shock and awe" bombing campaign, Rumsfeld's faster, lighter forces stunned the enemy by rushing to Baghdad in just three weeks.

But now an Army that has long wanted to retreat from heavy, slow tanks and Bradleys, which it once designed for use against the Soviets, suddenly needs them again. "If anyone would have told me a Humvee would be the platform of choice in a war, I would have told them they're crazy," says Gary Motsek, director of support operations for Army Materiel Command. His view was echoed last week by former Army chief of staff Gen. Eric Shinseki, who told an audience at California's Pomona College that Humvees were never intended for combat. But Motsek says the Army has adjusted faster than many people realize. Last fall, he notes, when the Army realized the gravity of the insurgency, engineers at the Army Research Lab at Aberdeen, Md., designed the add-on armor kits for the Humvees "over a weekend."

Dov Zakheim--who, until his recent departure, was the DoD's comptroller--told NEWSWEEK that another holdup has been an "antiquated" acquisitions system. Zakheim said the Pentagon fixed the problem only in the past six weeks with "joint rapid action cells," which allow contractors to waive regulatory red tape in wartime. Other Army officials complain that the nation does not have the industrial base any longer to produce equipment for a new kind of war. That's one reason so many supply trucks--seven out of eight, in fact--are still unarmored. The Army's "family" of medium trucks is now made by a single firm, Stewart & Stevenson of Sealy, Texas. All the features that make trucks driver-friendly--like a big front window--also make it a nightmare to drive on Iraq's lethal highways. So the Army has contracted both with its own depots and with outside firms to build applique armor kits. But, as with the Humvees, the extra weight can wreck suspensions and drive trains and overtax the engine's coolant system. "The last thing you want is a well-armored vehicle that breaks down," says Denny Dellinger, president of Stewart & Stevenson. So he's designing a whole new armored cab. "The Army is doing a helluva lot," Dellinger says, but the tactics of the insurgents keeps changing.

Yet some critics contend that, contrary to what Rumsfeld told Wilson, America is not going to war with the Army equipment it already has. They claim that vested interests at the Pentagon are sometimes obstructing the best firepower and equipment available. Why? In part because the Pentagon is still obsessed with its "lighter, faster" vision and is hyping new, ill-tested armaments like the Stryker fighting vehicle. Much older equipment, like treaded M113 personnel carriers, lies unused in arms "boneyards" although they could be up-armored far more cheaply than Humvees.

Among these second-guessers is Rep. Robin Hayes, a North Carolina Republican. Hayes told NEWSWEEK that "the secretary of Defense exhibited a remarkable lack of sensitivity" in his remarks. Hayes said he has been frustrated by delays in getting several heavier armored gun carriers to the light-gunned 82nd Airborne, which first requested them a year ago. Four such tank-treaded vehicles are still sitting in mothballs in Pennsylvania. Army Gen. Richard Cody approved the transfer last March. But then the Army decided to wait for a newer system mounted on a wheeled Stryker, though the system has been held up due to reliability issues, according to a recent General Accounting Office report. On Dec. 9, a day after Rumsfeld's Kuwait appearance, Hayes wrote him a letter saying, "I simply cannot understand why we are not equipping our soldiers and Marines on the front lines with every weapon in our arsenal."

Other defense insiders say that better armor has not been a high enough priority, at least until recently. After 9/11, Boeing ramped up production of JDAMs, its precise, GPS-guided bombs, from 900 a year to 3, 000 a month for use in Afghanistan. (This past week, in the middle of the armor furor, Boeing announced that it had delivered its 100,000th JDAM kit to the Air Force.) "If they could do it for bombs, why couldn't they do it for armor to save lives ?" asks Defense analyst Bill Arkin. Rumsfeld "could have awakened any morning in the last year and a half, determined to make sure every vehicle is properly armored and said, 'I want industry to jump through hoops to do it'," says one defense contractor. "I was infuriated he could be so cavalier." No doubt the Pentagon chief is getting on top of the problem now.