The white flag may be an international symbol of surrender, but in Fallujah it has become another tool of guerrilla war.
US marines on a foot patrol this weekend paid little attention to a man walking along the road and holding a white flag - a common sight as the conflict dies down and civilians pop up to scavenge for food and water.
But this time, US officers say, as the marines came by, the man dipped into an alley, returned with an AK-47 assault rifle, and sprayed the marines with bullets. Two Americans died, and others were wounded.
In a separate incident, marines were lured into an well-coordinated ambush by men with white flags who appeared to signal that they needed help. When marines got close, gunmen began firing from buildings high above.
The attacks expose the new risks in Fallujah as US forces begin shifting in coming days from combat search-and-destroy missions against insurgents, to fighting an enemy that can easily blend into an increasing number of civilians.
"I've been telling my marines: We are entering the most dangerous period now - even more dangerous than the breach [into Fallujah] itself," says Capt. Jer Garcia, commander of Bravo Company, 1st Battalion 3rd Marines. "It's too easy to think, 'We're not getting shot at all the time,' and take off flak jackets and [helmets]. Then, 'Wham!' "
So far, the gates of the city have yet to reopen to those who fled before the US assault. Even now, civilians are only permitted onto the streets from 8 a.m. to noon, and then only to collect food and water at distribution points or to take part in a nascent jobs program.
Some 300 men visited the Hadra Mohamadiya Mosque Sunday to get supplies - the largest number in a week. During the 20-hour-a-day curfew - an effort to prevent insurgents from coordinating with each other to mount attacks - anyone on the street is arrested.
Now US forces are viewing white flags with far more suspicion. "We're going to see these bogus surrender tactics. We're going to see more IEDs (improvised explosive devices). We've found many suicide vests, but I'm sure we have not found them all," says Lt. Col. Michael Ramos, commander of the 1-3 Marines, who control northeast Fallujah.
"They want a spectacular media event - they want a high number of civilian Iraqi or US military deaths," says Lt. Col. Ramos. "We're trying to deny them that opportunity."
The presence of civilians will "absolutely" change tactics, Ramos says. "There is a sense of urgency now to do as much as possible, and to do this right."
Indeed the hope is that progress in rebuilding Fallujah will lessen support for insurgents and help boost the standing of the interim Iraqi government, which announced Sunday that national elections would be held Jan. 30, 2005. The US has committed about $90 million to rebuilding Fallujah, and the interim Iraqi government has pledged $50 million toward the effort, according to military officials.
But over the weekend, insurgents in Baghdad and elsewhere in the Sunni Triangle stepped up bloody attacks. To the north, in Mosul, where the city was tense after a spike in violence a week ago, nine Iraqi soldiers were shot execution-style on Saturday. Sunday, US forces found two more bodies, one of an Iraqi soldier.
In Fallujah, commanders say that, so far, their tactics appear to be having some effect. The number of gun battles and mortar attacks has dropped in recent days, and over the weekend, troops here uncovered more weapons.
Marines found an IED factory over the weekend, laid out like an assembly line. Mortar and artillery bombs were lined up, then treated with solvent and their detonators taken out. Explosives could then be scooped out with scales to weigh the replacement blast.
Also included were what US officers said appeared to be materials for producing homemade napalm - a recipe that could have been drawn from the "Terrorist Cookbook," a favored text for Al Qaeda affiliates like the networks in Fallujah.
But the recent surge of violence across Iraq raises questions about the vitality of the guerrillas. Some houses used by the insurgents here have been smashed by airstrikes, and Sunday the trenches and spider holes dug for rebel defense remained empty.
But aggressive US searches - which have left some houses on fire as marines used grenades and even rockets to clear them, thus avoiding US casualties from hidden machine gunners - are yielding fewer guerrillas. As of today, marines will use mostly nonlethal means of breaching and clearing rooms and houses.
"It is still possible that the current wave of attacks is a 'one shot' effort that will burn out many insurgent resources," writes Anthony Cordesman, an Iraq expert at the Center for Strategic and International Studies in Washington, in a recent analysis.
"It is still unclear how many of those killed and detained in Fallujah were really hard-core cadres, and how many were recruited and trained only to stay and fight," he adds. "If most cadres left or escaped, and Fallujah and the other fighting acts as a major recruiting base, the military impact of Fallujah and tactical victories elsewhere could be limited."
Even in Fallujah, flushing out insurgents is no easy task, despite overwhelming US firepower. The Light Armored Reconnaissance (LAR) company launched two concerted attacks over the weekend, clearing blocks of suspect houses in conjunction with other units across the city.
Some weapons and a few people were found. In one case, four gunmen engaged a marine fire team and then escaped, marines believe. Another gunman popped his head over a rooftop twice and was engaged by marines.
The building was marked with smoke and rifle fire, and a Maverick rocket fired from a jet fighter crashed into the house. But a delay in approval for the air strike meant that, when the team returned to the site, the gunman had vanished.
Still, every raid and attack yield more weapons caches and intelligence about how this insurgency gripped Fallujah.
While US tactics will become more limited when civilians return, some aspects of the conflict may improve.
"The white flag is a big incident, a big security risk," says a US intelligence officer. "The risk will multiply [when civilians return], but so will the gains. That's when we can talk to people, and they can identify [insurgents]."
"It's going to be hard to get people to come forward, to cooperate," he adds. "But they will, because people do not want foreign fighters, and also they don't want Americans here. They are going to choose the strongest side - whoever has the power at the time, is who they are going to side with."