The American military even plans to build special, more defensible highways here, in its frustrating standoff with the makeshift munitions — "improvised explosive devices" — that Iraqi insurgents field by the hundreds to hobble U.S. road movements in the 3-year-old conflict.
Out on those risky roads, and back at the Pentagon, few believe that even the most advanced technology will eliminate the threat.
"As we've improved our armor, the enemy's improved his IEDs. They're bigger, and with better detonating mechanisms," said Maj. Randall Simmons, whose Georgia National Guard unit escorts convoys in western Iraq that are regularly rocked, damaged and delayed by roadside blasts.
Lt. Col. Bill Adamson, operations chief for the anti-IED campaign, was realistic about the challenge in a Pentagon interview. "They adapt more quickly than we procure technology," he said of the insurgents.
Casualty charts show a growing problem.
Better armor and tactics lowered the casualty rate per IED attack last year. But attacks almost doubled from 2004, to 10,593, meaning the U.S. death toll from IEDs still rose. Since mid-2005, an average of about 40 Americans a month have been killed by improvised explosives, twice the rate of the previous 12 months, according to icasualties.org, an independent Web site that tracks casualties in Iraq.
Meanwhile, the overall U.S. death rate held steady from 2004 to 2005, making IED fatalities comparatively more significant. Last month, for example, 36 of 55 American military personnel killed in Iraq were IED victims.
The bomb makers have the White House's attention. In a radio address on Saturday, Bush said roadside bombs "are now the principal threat to our troops and to the future of a free Iraq."
Bush said in a speech Monday that Iran had supplied IED components to Iraqi groups, but U.S. officials have presented no evidence to support that, nor did Bush explain why Shiite Muslim Iran would aid Iraq's Sunni-dominated insurgency.
For their IEDs, Iraqi insurgents, who are believed under the direction of former military and intelligence officers, rely on the tons of military ordnance left over from the era of Saddam Hussein, and on store-bought electronic and other items for ignition systems.
The Pentagon's upgraded Joint IED Defeat Organization is getting a sharply increased $3.3 billion this year to foil the often rudimentary weapons, which the Iraqi resistance generally fashions from artillery and mortar rounds. The "JIEDDO" staff of explosives experts and others will almost triple, to 365.
From 2004 to 2006, some $6.1 billion will have been spent on the U.S. effort — comparable, in equivalent dollars, to the cost of the Manhattan Project installation that produced plutonium for World War II's atom bombs.
The investment has paid dividends in Iraq: in "jammers" installed on hundreds of U.S. vehicles to block radio detonation signals; in massively armored Buffalo vehicles whose mechanical arms disable roadside bombs. Forty-five percent of emplaced bombs are cleared before detonation, the U.S. command says.
In one initiative showing how seriously it takes the threat, the Defense Department proposes spending $167 million to build new supply roads in Iraq that bypass urban centers where convoys are exposed to IEDs.
But experts like the Air Force's Bob Sisk, an explosives-disposal specialist whose teams are daily disarming IEDs north of Baghdad, said the most important investment is in intelligence.
"The idea is to get the pieces of an IED to `Sexy,'" said this senior master sergeant.
"Sexy" is CEXC, the Counter Explosive Exploitation Cell, a secretive group at Baghdad's Camp Victory that is building a database on IED incidents, in search of patterns and defenses.
"The initiation system" — detonators — "is always of interest," Sisk said. The bomb makers have progressed from using washing-machine timers and pressure switches for initiating explosions, to cell phone and walkie-talkie signals, and even infrared beams.
The IED analysts are vitally interested in placement-concealment tactics. The bombs can be found in roadside garbage bags or sandbags, in piles of rocks, buried in holes, in sheep or dog carcasses. One was recently discovered disguised as concrete street-side curbing.
Hoaxes are a peril. "The enemy's very smart," said Capt. Peter Weld, Sisk's commander. "They plant a harmless device that soldiers find and gather around, and then they hit them with a real device nearby."
"Shaped charges" are also proliferating — killer explosives that direct armor-piercing projectiles into U.S. vehicles.
The Pentagon's Adamson said new ways to neutralize IEDs on the ground are critically important. But "we'll never keep up with the enemy's agility," and the top priority must be "taking down the human component — the financiers, the suppliers, the bomb makers."
For that, he said, "our goal is to get better technical and forensic data off the ordnance" — from digital photos, measurements, explosive residue, fingerprints, debriefings of troops on the scene.
The U.S. command claims significant success, saying it has captured or killed 41 bomb makers since November. But soldiers still face the bombs at seemingly the same rate.
The Georgia National Guard's Sgt. Robert Lewis couldn't help being impressed while on duty in central Iraq.
"There's a road we called IED Alley that the ordnance disposal guys would clear regularly," Lewis, 47, of Carrollton, Ga., said at his current post in western Iraq. "But no sooner would they reach the end of that stretch" — eight miles — "than the insurgents would be planting IEDs again at the beginning."