For U.S. troops in Iraq, homemade bombs are the main killers, despite the hundreds of millions of dollars the Pentagon has spent trying to curb the weapons made from simple, easy-to-obtain materials.
As September shapes up as one of the deadliest months in Iraq for U.S. troops, the Pentagon estimates it is finding 40 percent of roadside bombs before they explode. But military officials say the problem persists even with teams of technical experts working to defeat the threat.
In the first 22 days of the month, at least 63 members of the Army, Marine Corps, Navy and Air Force died, Pentagon casualty reports show. With a week to go, September is the fifth-deadliest month since President Bush declared an end to major combat operations on May 1, 2003.
In addition, September has seen the beheadings of two American civilians and insurgent attacks that have killed dozens of Iraqi police and hundreds of civilians.
More than 7,400 soldiers have been wounded since the war began, of whom 4,026 were unable to return to duty, according to Pentagon figures.
The pace of U.S. military deaths has grown each month since the American occupation force handed over political control to an interim Iraqi government June 28. Both Bush and military leaders like Gen. Richard Myers, chairman of the Joint Chiefs of Staff, have said they expect the violence to grow further before January elections.
"Clearly the incidents of violence are up" this month, Defense Secretary Donald Rumsfeld told the Senate Armed Services Committee on Thursday. He predicted violence would worsen because the insurgents are bent on stopping creation of a legitimate government.
At least 15 of the first 29 Army deaths in September were caused by homemade bombs, which the military calls improvised explosive devices. Most are hidden or disguised along roadways used by U.S. military convoys. Others are delivered to their target in cars and other vehicles.
The Marine Corps does not announce the specific cause or place for its deaths, but Pentagon officials say homemade bombs are accounting for roughly the same share of Marine deaths as for the Army: about 50 percent. That would equate to at least a dozen Marines this month.
The Associated Press, quoting an unnamed senior Army officer at the Pentagon who monitors progress against the insurgency, reported that the 155mm artillery shells and other explosives used to arm the improvised bombs are so easily available that the supply cannot be stopped, even though ammunition dumps are under surveillance. The officer discussed the problem only on condition that he not be identified.
The officer estimated hundreds of millions of dollars have been spent so far trying to counter the threat, to no apparent effect.
Within 24 hours of a reported attack by one of the bombs, a team of military forensics experts and other specialists is dispatched. They inspect evidence, interview troops and assess the technique used by the attackers. The scene is sketched digitally and fed to experts who search for patterns of attack.
Remotely piloted surveillance aircraft are being used not only to search for attackers, but also to monitor places where bombmakers are likely to obtain explosives.
That effort has enabled U.S. troops to find an estimated 40 percent of homemade bombs before they explode, but it has not stopped the killing and maiming. Indeed, bombs rigged to explode in cars or along U.S. supply convoy routes continue to kill or wound American troops and Iraqi security forces almost daily.
The most dangerous part of Iraq in recent weeks has been Anbar province, which includes the restive cities of Ramadi and Fallujah west of Baghdad as well as a long frontier with Syria. At least 30 U.S. troops, mostly Marines, have been killed in Anbar this month.