LSA ANACONDA, Iraq — It was the biggest operation conducted by the 100th Battalion, 442nd Infantry in Iraq.

Over the three days of "Cobra Strike," about 140 soldiers from the "Go For Broke" battalion joined up with 100 Iraqi army soldiers and 80 U.S. Air Force personnel to comb through two villages west of Logistics Support Area Anaconda for militants who fire mortars and rockets at the big air base.

There was success: About a half-dozen suspects were detained, and on Day 3 in the village of Hamadi, the joint effort turned up a cache of 60 mm and 82 mm mortars, and four rocket-propelled grenade launchers and rounds.

"We believe we got the mortar firers, and we believe we got the cell leader," said Maj. Mike Peeters, 42, from Honolulu, the battalion's executive officer.

But the progress was offset by the death of a Hawai'i soldier, the first from the state since the 29th Brigade Combat Team arrived in Iraq nearly six months ago.

Sgt. Deyson K. Cariaga, 20, of Kalihi, was working in intelligence with Air Force counterparts when a roadside bomb exploded beneath his Humvee on July 8, the last day of Cobra Strike.

"They were moving off the final objective from a very successful mission when they hit the IED (improvised explosive device)," Peeters said.

There is little in the way of direct attacks with small arms on U.S. troops in the vicinity of Anaconda, an air base carved out of farmland about 50 miles north of Baghdad.

But mortar firers and roadside bomb makers stay very busy.

Militants have used everything from dead animals to piles of roadside gravel to hide bombs, often made from artillery shells. It can take less than one minute on the side of the road to plant such a device.

"This is a combat zone where people are trying to kill us," said Maj. David Weissberg, 39, from Kapolei, the 100th Battalion's operations officer. "They are not brave enough to go toe to toe with us, so what they do is place IEDs and run away, and that's what happened here."

Insurgents show some bravado, firing mortars at the 15-square-mile base that usually land harmlessly, and units like the 100th, whose area of responsibility extends around three sides of the base, have to root them out.

"We're not going to be able to destroy the enemy. There's always going to be IED attacks," said battalion commander Lt. Col. Colbert K.H. Low. "What we want to do is minimize those as much as possible."

Cobra Strike was preceded by Operation Island Torch, a helicopter assault mission to two islands in the Tigris River to the north of the base to look for weapons caches and mortar firing positions.

None was found. In that mission, the targets were several individuals collectively referred to as "Six-round Charlie" for the number of mortars fired at Anaconda.

To the west, it's a different foe, firing 60 mm mortars and 57 mm rockets.

"One round (fired) and then they're gone," Peeters said. "They come in under the cover of darkness, and may have some family (in the village). They probably have some ties locally, and have the ability to move quickly. There have been a couple of cases where they try to intimidate the local sheiks."

The response is full spectrum, with intelligence teams trying to get leads; civil affairs providing aid and trying to win over residents; and the 100th Battalion, in this case, cordoning off and securing sections of the two villages while the Iraqi army conducts a search of about 80 homes.

When Cariaga was killed, "they were coming back from doing an outstanding job," Peeters said.

"No doubt what they did out there saved lives (on LSA Anaconda) by showing who was shooting and detaining those guys so they can't shoot again."