The fate of three missing American soldiers, apparently captured after a weekend Al Qaeda ambush, remained uncertain Sunday, but the mission to find them demonstrated a new reality for US forces: They are facing a deadlier Iraq as their numbers rise.
The Saturday attack that killed four soldiers and an interpreter in Mahmoudiya, south of Baghdad, follows a string of strikes on US forces over the past month, particularly in volatile Diyala Province north of Baghdad, resulting in high casualties. In April, 104 Americans were killed, the deadliest month this year, and so far this month 43 US soldiers have died, according to icasualties.org, a website that tracks Coalition deaths in Iraq. In April 2006, the site reported, 76 Americans were killed.
Al Qaeda forces in Iraq "are changing their tactics because of the American surge," says Toby Dodge, an expert in Iraq affairs at the International Institute for Strategic Studies in London. "They are shifting their fight to two fronts, the Iraqis and the Americans," he adds, with the dual aims of advancing Iraq's sectarian violence and influencing the US military strategy by striking high-profile blows.
President Bush has warned in speeches recently that troops would face higher danger in Iraq and that US casualties were likely to rise as the military shifts to tactics taking soldiers into insurgent-dominated areas and closer contact with enemy forces.
But the ambush in an insurgent stronghold known as the "triangle of death" suggests that Al Qaeda in Iraq is pursuing its goal announced earlier this year of stepping up attacks on US forces.
The intense search operation following Saturday's attack, involving thousands of US and Iraqi forces and employing everything from field sweeps and checkpoints to infrared heat-detecting technology and unmanned drones, is in part standard US military procedure in the case of captured soldiers.
The hunt also reflects concerns, born of experience in Iraq, about the methods the Iraqi insurgency and Al Qaeda in particular use to turn captives into propaganda tools.
Saturday's strike echoes a June 2006 attack in the "triangle of death" that was one of the rare cases of US soldiers in Iraq taken captive. In an incident at a fake checkpoint not far from Mahmoudiya in the town of Yusefiya, one soldier was killed and two were seized. Their severely tortured bodies were found days later.
In that case, an Internet statement posted by the Mujahideen Shura, an umbrella insurgent group including Al Qaeda in Iraq, claimed the killings "carried out the verdict of the Islamic court."
After the April truck bombings in Diyala, Internet postings by the Islamic State of Iraq claimed the attack and announced creation of a "cabinet" and a "ministry of war."
"Let the enemy expect more from the ministry, with power and might from the glorified God," one posting said. "The suicide brigades are continually increasing" in response to the growing "intruding brigades," an apparent reference to the "surge" of about 25,000 US troops to the Iraq fight.
The evolution of attacks by the Sunni insurgency, including Al Qaeda, to higher-profile, higher-casualty operations reflect both the squeeze brought on by the US surge and frustrations with civilian rejection of Al Qaeda, Iraqi sources say.
The site of Saturday's attack, for example, is across the Tigris River from the area assigned to one of the new US brigades in the Baghdad area.
The military is charged with cutting off the flow of explosives into Baghdad over the major southerly highway there, as well as with disrupting insurgent cells from planning attacks.
At the same time, incidents of retaliation against Sunni civilians for rejecting Al Qaeda are multiplying.
On Saturday, a sheikh of the Jabour tribe and several relatives were killed by Al Qaeda in the Mohammediyah village between Ramadi and Fallujah, in Anbar Province, after they called for cooperation with official security forces against Al Qaeda, the Al Hurra television station reported. Execution killings are also increasing in Sunni Fallujah, suggesting rising Sunni-on-Sunni violence.
"It is becoming more common for Al Qaeda to strike back in revenge at people who dare to turn against them," says Iyad Samarrai, a Sunni member of Iraq's parliament.
At the same time, the multiplying bomb attacks on infrastructure like bridges and electrical networks, as well as on public places like markets, is an attempt to feed sectarian divisions while convincing all Iraqis that the government is weak and ineffectual, he says.
"We don't know exactly who is behind these attacks, whether it is Al Qaeda or other groups or even the intelligence of some other countries, but we can say in any case that it is done to show that the government is unable to protect the people and these sites," Mr. Samarrai says.
This weekend two bridges spanning the Tigris River in the south of Baghdad were hit by truck bombs. The two blasts follow last month's bombings of the historic Sarafiyah bridge in north Baghdad and the Jadriyah bridge in the south. The Sarafiyah bridge, a key link between Shiite and Sunni banks of the Tigris, collapsed into the river.
"Al Qaeda's objective for a long time has been to drive a wedge between Iraq's sectarian communities, between the Shiites and the Sunnis, and this tactic advances that by making connections between them more difficult," says Mr. Dodge.
The area south of Baghdad, like Diyala to the north, presents different challenges than the more uniformly Sunni Anbar Province to both Sunni insurgents on the one hand, and the Iraqi and US militaries on the other, Dodge says.
"The population is much more mixed, so the sectarian divide is layered over everything. That frustrates the ability of the Iraqi authorities to establish a presence," he says, but "Al Qaeda has also found it more difficult to operate there."
The mayor of Mahmoudiya, Mouayad Fadhil, reported Sunday that people in his town are cooperating with authorities and offering any information they have on Saturday's attack.
Mr. Fadhil and his town are no strangers to the ugliest sides of this war. Last March Mahmoudiya was the scene of a rape and killings by US soldiers that rocked the US military and a violence-numbed Iraq. Six US soldiers took part in the rape and murder of a teenage girl and the murder of her sister and parents.
Dodge says Saturday's attack demonstrates Al Qaeda's ability to adapt to circumstances and bounce back from setbacks. "They've been forced to change their tactics and forced to change their areas of geographical operation," he says, "but they are a long way from defeated."