A commander at the base where many of the Marines killed in Iraq (search) this week were stationed expressed his condolences Thursday to their families, and said troops will press on with their mission despite the losses.

"I can tell you that where we operate, we're doing the job, we're performing our mission, we're killing the bad guys and we're making life better for the average Iraqi people in the western part of Iraq," Maj. Gen. Keith Stalder said.

A wave of violence in Fallujah (search) and neighboring Ramadi (search) has claimed the lives of at least 15 Marines since Monday. The Defense Department has confirmed that nine Marines killed by hostile fire were based at Camp Pendleton (search).

While he declined to discuss casualties, Stalder said he would tell the families of the dead Marines "how deeply saddened we are by the loss of this fine young man or woman and reassure them that the cause that they made the sacrifice for was a worthy cause."

The increased attacks on troops occupying areas west of Baghdad were due to the Marines' strategy of challenging insurgents in places where they have gained influence, according to a statement from the 1st Marine Expeditionary Force (search), based at Camp Pendleton.

"We went fully prepared to engage and kill the enemy wherever they chose to fight. We're doing that right now. We're winning every firefight we engage in," Stalder said during a news conference at the gates of Camp Pendleton, the sprawling base north of San Diego.

Stalder, the deputy commander of the 45,000-member 1st Marine Expeditionary Force, is stationed at Camp Pendleton.

He said the fighting led Marines Wednesday to a mosque in Fallujah. While mosques are protected under the rules of war, Stalder said, the mosque lost that status when a "platoon-sized" group of insurgents -- roughly 40 people to 60 people -- fired upon Marines from inside the complex.

"If anybody shoots at us from a mosque, we're going to do what we need to do to protect ourselves," Stalder said, adding that commanders take pains to avoid damaging mosques and other protected structures. "The cases where we've had to do that, we go back later to see if we can help fix the damage that has been done in a way that sends a message to the locals."