The thrust by about 1,000 U.S. Marines, soldiers and sailors and 100 Iraqi troops, called Operation Sword, centered on towns along the Euphrates River about 90 miles west of Baghdad. Marine spokesmen have said the operation, like other recent sweeps farther west, is aimed at driving insurgents out of towns and disrupting their ability to move guerrillas, weapons and supplies from neighboring Syria into western Iraq and other parts of the country.

''Since the combined force of Marines and soldiers entered the city of Hit on Tuesday, there has been no significant resistance or opposition,'' said Lt. Col. Christopher Starling, operations officer with the Marines' Regimental Combat Team 2. ''The people have been overwhelmingly receptive and have assisted coalition and Iraqi solders in locating roadside bombs and weapons caches.''

A Marine statement said there had been no fighting reported Thursday, no buildings destroyed and no air strikes conducted.