The operations have focused on locales along the border with Syria and in small towns surrounding Fallujah that are part of a clandestine network of support for fighters locked in a bloody, two week standoff with marines, the official said.

"There have been specific raids on known inidivuals who are providing those weapons, those finances, which in turn has led to additional information on how those organizations are structured and equipped," said the official, who spoke on condition he not be identified.

"Many of those operations have been along the border region with Syria," the official said.

"There are a lot of small towns around Fallujah that also have been providing support for the insurgents," he said.

The marines, he said, "have been really successfully in heading much of that off.

Five marines, however, were killed Saturday in a battle near the Syrian border after they were lured into an ambush in the town of Husaybah.

The attack on a Marine patrol set off a 14-hour firefight that drew in a second marine unit backed by helicopters, according to a St. Louis Post-Dispatch account filed by a reporter embedded with the marines.

Senior Pentagon officials have stepped up complaints in recent days that Syria is turning a blind eye to the movement of foreign fighters across its border with Iraq.

"We know that the path, pathway into Iraq for many foreign fighters is through Syria. It's a fact. We know it. The Syrians know it. The Syrians can do more to stop it," General Richard Myers, the chairman of the Joint Chiefs of Staff, said on CNN television Sunday.

"I want them to cut off this flow of foreign fighters and go after the facilitators in Damascus that help these people get the right papers or financing and the transportation to the border," he added.

In Baghdad, coalition military spokesman Brigadier General Mark Kimmit said the 1st Marine Expeditionary Force has made "a tremendous effort ... to control the border with Syria."

"These engagements with persons, either in the town of Husaybah or along the Syrian border, demonstrate that the Marine expeditionary force is out there patrolling the border and ensuring that the traditional ratlines, as we call them, coming in from, for example, that portion of Syria are being patrolled," he said.

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