MARJAH, Afghanistan — The Marines have found bloody clothes and spent bullet casings and bombs meant to kill them. They’ve heard bullets flying overhead and seen muzzle flashes in tree lines.

In this southern Afghan town that coalition forces seized from Taliban fighters eight months ago – and are still clearing – you don’t have to go far to find the insurgency. But finding insurgents is another story altogether.

“The only time we see them is when we’re in contact” in a gunfight, said Cpl. Chuck Martin, 24, of Middletown, R.I.

And even catching a glimpse of them during gunbattles can be rare.

When U.S.-led coalition forces poured into Marjah in February, they ended years of Taliban control here. But the Taliban never left – they simply went underground, blending in among civilians, taking advantage of the region’s terrain of agricultural fields and irrigation trenches to stage daily ambushes of American patrols.

Today, U.S. troops are knee-deep in a classic guerrilla war, in what sometimes seems to be an endless turf battle against an often-invisible enemy that fights one minute, pretends to farm the next.

“I’ve seen the Taliban a couple of times, but it’s only for brief seconds,” said Lance Cpl. Benjamin Long, 21, of Trussville, Ala., who knew they were close on one recent patrol when machine gun rounds suddenly began kicking up dust near his feet. “It’s like fighting ghosts. They’re in and they’re out. They’re quick. They’ve been doing this a long time (and) they’re good at it.”

When U.S. forces go out on patrol, children and farmers come out of their homes and watch them closely. Some are just curious. Others use cell phones to tell insurgents what the Americans are doing.

When gunbattles erupt, Marines must simultaneously take cover and figure out where the Taliban are so they can return fire. They first listen to the crack and pop of gunshots, then look for muzzle flashes – although sometimes gunmen are hiding in foliage so thick they can’t even see those.

Firefights often last around 15 or 20 minutes because the Taliban know how long it takes for troops to call in helicopter gunships or mortar barrages, Marines say. If air support doesn’t arrive, the gunmen often start shooting again.

After one recent firefight, one Marine squad scooped up spent bullet cartridges from a compound insurgents had just fired from. It was the first time they’d found such a trace since arriving in July, said Sgt. Jeffrey Benson, 34, of Medina, Ohio.

“Usually they take everything after a firefight,” Benson said. “They’re real good at getting their dead and injured out.”

During another 20-minute battle two days later, guerrillas ambushed Marines from the broken windows of a small, abandoned school compound. When Marines pushed up to it, they found more spent bullet casings – but again, no dead or wounded.

Soon, they began taking fire again from two more locations; the insurgents had merely withdrawn and found somewhere else to shoot from.

“It’s like a little cat-and-mouse game,” Martin said. “We try and get them. They hide their weapons … then they just come back to the same location, pick up the same rifle, shoot at us again.”

During the second gunbattle, Marines radioed for a mortar bombardment to suppress their attackers. A wave of shells exploded along the outer wall of a compound, shaking the area and kicking up vast brown clouds of dust.

When Martin arrived afterward to assess the damage, he found the father of a family who claimed he’d seen no Taliban at all – a common refrain.

“It’s one of the most frustrating things out here,” Martin said. “We know there’s Taliban in the area, and they’re like, ‘No, they’re not.’ “

U.S. forces across Afghanistan say the key to turning the tide in the nine-year war rests largely on civilians turning against the Taliban. In Marjah, though, that has yet to happen on any significant level, despite the steady presence for more than eight months of two Marine battalions and their Afghan counterparts.

“They always ask us, ‘why do you need our help anyway? You’re the ones with the guns … you have the planes, you have the helicopters,”‘ Martin said. “They don’t realize that just the information that they give us is the most helpful thing.”

Some residents, having heard about President Barack Obama’s pledge to begin withdrawing Americans from Afghanistan next summer, believe U.S. forces are not going to be in Marjah for long, Marines say. And whenever U.S. forces leave, the people who live here think they’ll be left with an ineffective and undedicated force of Afghan police and soldiers – and of course, the Taliban, who are already among them.

“They don’t know who to trust,” Long said.

Neither do the Marines.

The base was recently attacked in a six-hour firefight that saw insurgents – with clear knowledge of the base’s interior – angling their machine gun fire up and over the walls in an attempt to strike the vulnerable tents inside.

During a patrol one week later, Marines were astonished to find a crude drawing of what was clearly the exterior of the base, scrawled in white chalk on a wall in a man’s home. Lines of fire were drawn at what appeared to be the post’s guard towers.

“This looks a lot like an attack plan to me,” said Lance Cpl. Patrick Cassidy, 23, of Stroudsburg, Pa. The Marines’ base was only a couple dozen (yards) away, on the other side of a wide canal built with U.S. aid money 50 years ago.

Bismullah Nazir Ali, the home’s owner, pleaded innocence. No Taliban had been there or in his fields, he said.

As he spoke, another gunbattle raged a few hundred meters away. Cobra attack helicopters were pounding targets with rockets that shook the area.

“Those are just flowers, children’s drawings,” Ali said before he was hauled off.