The white Suburban with the bullet riddled windshield looked suspicious, half-hidden just off the road, as the US Marine convoy passed by on Saturday.
But it was the killer's look that shocked Capt. Jer Garcia.
"I looked him right in the eyes - and when he looked down at his steering wheel, I knew something [was coming]," the company commander recalled. In just seven seconds, Captain Garcia had reached for his handset and had radioed a warning to the convoy.
But it was already too late. The Suburban pulled into the convoy, and the driver detonated the suicide car bomb next to a troop carrier truck, causing eight deaths. Another marine was killed elsewhere in Iraq, making Saturday the deadliest day for US forces since May.
"The next thing I know, I saw the explosion," says Garcia, from Honolulu, Hawaii. "The Suburban was gone, and my marines were incinerated."
The casualties show how the learning curve for US forces in Iraq continues to rise, even as they struggle to prevent a spreading insurgency from spiraling further of control.
But it also comes as US Marine and Army elements prepare for a possible all-out offensive against the insurgent nerve center of Fallujah that commanders hope will stanch the insurgency. Two months of almost-nightly airstrikes in the city gave way Saturday to a probing ground operation southeast of the city, where marines sparked a three-hour firefight and gained a measure of their opponents.
By comparison, the Marines' next operation "will be more complex, more dangerous, and it will last longer," Lt. Col. Michael Ramos, a battalion commander, told his staff Sunday to conclude the after-action briefing. "We don't know when it's coming; we know it's coming soon.... Rest your marines, and get them ready for the fight."
That advice echoes the tough talk of senior US commanders and Iraqi officials. On Sunday, Iraq's interim prime minister, Ayad Allawi, said that while he still held out hope for a negotiated solution, "our patience is running thin."
Officials are making it clear that any Fallujah offensive will not be called off, like the attempt last April that was stopped before it could finish.
"If we're told to go ... it's going to be decisive," Brig. Gen. Dennis Hejlik, the deputy commanding general of the 1st Marine Expeditionary Force (1 MEF) in charge of western Iraq, said over the weekend. "We're going to go in there, and we're going to whack them."
Concerns remain about whether even a complete defeat of insurgents in Fallujah can stop the insurgency that has weakened security across Iraq to the point that it undermines the possibility of elections slated for January.
A key target is Abu Musab al- Zarqawi, the Al Qaeda-linked Jordanian militant, who has claimed responsibility for numerous explosive attacks and the kidnapping and killing of hostages.
"Just because you chop off Zarqawi, the head, doesn't mean you are going to stop [the insurgency]," says Maj. James West, a senior 1st MEF intelligence officer. "You've got to stop the motivation for why people are coming in to fight."
That message is not lost on the combat regiments gearing up for war around Fallujah. Sunday, Marine platoons practiced urban warfare tactics among some gutted buildings. Armored units are training alongside infantry companies; issues of overloaded radio networks are being worked out.
"You have to learn fast in this environment," says Lt. Colonel Ramos, from Dallas, Texas. "The enemy is willing to sacrifice lives. They are willing to martyr themselves for what they believe is an important cause.... The rules of war don't apply for them."
As an example, Ramos says an ambulance that he suspects was another car bomb circled Marine positions Saturday night, and was finally forced away with warning shots and flares.
"It was looking for a weakness, looking for a vulnerability, and it attempted several times to penetrate our lines," says Ramos. As marines have learned more about insurgent tactics - including from the Saturday firefight, which they say drew out a "significant" number of foreign fighters - the insurgents have learned more about them.
"Obviously, [marines] are going to be frustrated, they are going to show emotion, when they lose their friends, when they lose their fellow marines," says Ramos, of the company struck by the suicide bomb.
Indeed, in the course of the briefing described earlier, when the focus turned to compensation paid to Iraqis for civilian damage, one angry officer asked whether that should be a priority when "there are people out there who want to kill us," and so many marine families are mourning their dead.
"You aim the violence at the people who deserve the violence, not civilians," Ramos told him.
"We're only going to win this fight if we target terrorists, and reinforce and help the common, decent people," Ramos said later. "The majority of Iraqis are common, decent people - they want the same things that we do: life, liberty, and the pursuit of happiness."
But that is tough for some marines to accept after the suicide bomb. Captain Garcia says his biggest challenge will be funneling the emotions of his marines, after the losses Saturday.
"As a commander, it's my job to make sure that anger doesn't turn into hatred, and is focused instead on the task at hand," says Garcia. "If we turn to hatred, then we are no different from them."
A similar message came Sunday from Chaplain Kenny Lee, of Orlando, Florida, as he held a Sunday service in a makeshift chapel. He went to the site of the suicide bomb, to encourage marines on guard there.
"They need to vent, and it's natural in this environment, for them to say 'We should kill them all,'" says Chaplain Lee. "I encourage them to vent, to get it out. Now it's just emotions."
The word in the chapel aimed to both console - after the bombing - and to bolster for the upcoming battle.
"Have I not commanded you?" chaplain Lee read from the Book of Joshua. "Be strong and courageous. Do not be terrified; do not be discouraged, for the Lord your God will be with you wherever you go."