RAMADI, Iraq — Pfc. Phillip Busenlehner still thinks about his choice. Unbidden, in quiet moments, it creeps into his head.
The 20-year-old Marine from Birmingham, Ala., was standing guard at a combat outpost in central Ramadi when he saw a man 400 yards away.
"He was popping around the corner, back and forth, back and forth," Busenlehner remembered. "He was observing the post. But that far back, how much could he really be observing?"
Was he trying to figure out if it was safe to move? Or was he plotting an attack? Hand near the trigger, Busenlehner faced the most difficult choice a soldier or Marine must make in a war: to kill, or not?
With insurgents hiding among ordinary Iraqis, that decision often must be made in a split second. The wrong choice could mean a guerrilla gets a chance to lay a roadside bomb that kills more Americans or Iraqi civilians. Or it could mean an innocent Iraqi dies at the hands of Americans and a whole neighborhood turns against U.S. forces, setting back the war effort and putting more insurgents on the street.
Busenlehner, one year into his four-year stint with the Marines, radioed his squad leader. He got permission to shoot. Now, the choice was his.
In another part of the city, near one of the most dangerous intersections in Ramadi -- the military calls it "Firecracker" -- two squads of Marines gathered in an Iraqi family's living room. The neighborhood had seen some spectacular firefights between insurgents and Americans. It was also a prime area for improvised explosive devices, or IEDs, the roadside bombs that have proved deadly to U.S. troops in Iraq.
The platoon had been visiting families in the area, knocking on doors, trying to collect information and build goodwill, the first step toward trying to take the region back from insurgent domination.
The conversation wound down, but the Marines remained, waiting for other military units to move through the area. The Iraqi homeowner began flipping channels on his television. He settled on an English-language movie with Arabic subtitles. Lt. Ryan Hub, the platoon leader, turned toward the television and groaned. The TV was showing American soldiers pinned down as they were attacked by waves of men with AK-47s and rocket-propelled grenades.
" 'Black Hawk Down,' " said Hub, 25, originally from Calhoun County, S.C. "It's not a good sign, man."
Moments later, Marines on top of the house sent down an urgent message: They had spotted, a few blocks away, two men on another roof that overlooked the Firecracker intersection.
Hub ran upstairs. The Marines' night-vision equipment gave them a clear view of the men. They could be IED triggermen. But the night was hot and many homes in the neighborhood had no power. Families without fuel for their generators stayed cool any way they could. Some chose to sleep on their roofs.
Hub faced a choice.
"It's a difficult decision," Hub said, as his Marines kept watch on the two men. "More than likely if they were to do anything, they would trigger an IED. But there is no way we could confirm that from here. We can't just shoot these two people. And that is one of the problems of urban war."
A poster has been hung at each of the Marine outposts around Ramadi. Titled "Roadmap to Success," the poster outlines the tenets of the fight in Iraq, as the Marine Corps sees them.
"The Iraqi people are not our enemy, but our enemy hides amongst them," the fifth tenet reads.
Below that line, the poster lists two corollaries.
"You have to look at these people as if they are trying to kill you, but you can't treat them that way," one says.
"Be polite, be professional, have a plan to kill everyone you meet," the other says.
Marines in Ramadi sometimes joke that they wish they were fighting in World War II -- the Germans at least wore uniforms. Here troops have to look for more subtle clues.
"You can tell a good person from a bad person," said Lance Cpl. Michael Nichols, a 21-year-old member of Kilo Company from Martinsville, Va. "If they are innocent they will cross the alleyway and not look at us."
The toughest calls are the peekers. In Ramadi, soldiers and Marines will see Iraqis peek from behind a building. Are they nervous because they're afraid they could be shot mistakenly? Or are they up to no good? If a Marine waits too long before deciding, the next time the man peeks out from behind the building a rocket may be flying at his guard post.
"This is a thinking-man's job," said Nichols' partner, Lance Cpl. Robert Dean, a 21-year-old from Elkton, Va.
Nichols agreed. "There is no set rule," he said. "You have to have common sense. This place revolves around common sense."