"As our forces moved to receive this surrender in an honorable way, they were attacked and sustained casualties," said Brig. Gen. Vincent Brooks, deputy operations officer at Central Command, at a briefing Sunday in Qatar.
Fewer than 10 Marines are reported to have died in the battle. An unspecified number of others were wounded. Embedded news crews say as many as 50 Marines were wounded.
The Marines destroyed eight tanks, some anti-aircraft batteries along with "a number of infantry" said Lt. Gen. John Abizaid, deputy commander of coalition forces in Iraq.
"The Marines were successful, they defeated the enemy," Abizaid said.
"It was one of the few times we've seen regular forces fight," he said. "Suffice it to say it was a very sharp engagement."
The fake surrender was one of several incidents "in which there were types of behavior only I can only describe as ruses," Abizaid said.
A Pentagon official said Saturday that 700 Iraqi troops were in surrender formation waiting for U.S. troops to arrive. It was not clear Sunday whether those were the same Iraqi forces who attacked the Marines.
In one incident Iraqi troops raised a flag of surrender but then launched an artillery attack. In another troops disguised in civilian clothes appeared to welcome U.S. forces and then ambushed them, he said.
"The coalition encountered pockets of determined resistance by irregular Iraqis forces, who in some cases fought in civilian clothes or in modified commercial vehicles," Brooks said.
"We, of course, will be much more cautious in the way that we view the battlefield as a result of some of these incidents," said Abizaid.
Irregular Iraqi forces ambushed an unprotected convoy of U.S. supply vehicles in southern Iraq when it apparently took a wrong turn. A Marine combat unit arrived at the end of the battle, rescuing the "remnants of the convoy" and fighting off the remaining Iraqi forces. The ambush left six vehicles demolished. Four soldiers who survived the ambush were evacuated for medical treatment, Abizaid said.
An undisclosed number of U.S. soldiers have been taken prisoner. Twelve were unaccounted for and some may have been executed, according to Pentagon officials and gruesome video and photographs released by the Iraqi government.
The pictures showed around six dead soldiers on the floor of a building. At least one American soldier was shot through the forehead. The wound was pictured in a close-range photo.
"This is a clear violation of the Geneva Convention," said Abizaid, who called the images "disgusting."
The Pentagon asked news organizations Sunday not to use the images or identify the soldiers involved until their families have been notified.
Abizaid said the coalition has two Iraqi generals in custody and they are providing information to the force.
Areas previously thought to be under coalition control continued to be scenes of battle. There remained resistance in the port city of Umm Qasr and in Basra, in addition to fighting around Nasiriyah. In some cases the fighting was happening at the rear of U.S. forces as they marched toward Baghdad.
"I'm certain that the land force commanders will make some adjustments," Abizaid said.
The fourth day of the ground war was the toughest yet but nothing the military was not expecting, he said.
"We have to understand that in many conflicts in our nation's history, and in the history of our coalition partners, there have been days much, much worse than this by any stretch of the imagination," Abizaid said.
The British Three Commando Brigade and the U.S. 15 Marine Expeditionary Unit were "mopping up" the last remnants of resistance on the al-Faw peninsula and in Umm Qasr, said Maj. Gen. Peter Wall, a British commander.
"I think all of us should understand that in these very large, urban areas, it will take a long time to ensure that various regime-support elements are brought under control," Abizaid said.
He said special Republican Guard units and "irregular" militia groups seemed to be in the cities and were responsible for the resistance.
"I don't think that you'll find over time that these groups will create a significant difficulty for the overall achievement of the military objectives of the coalition," he said. The coalition comprises 240,000 U.S., 45,000 British, 2,000 Australian and some Polish troops.
"We certainly have sufficient force," he said.
A U.S. Patriot missile Sunday accidentally shot down a British RAF Tornado GR-4 jet returning from a bombing mission against Republican Guard units near Baghdad. The incident is under investigation.
Coalition forces have seized the Tallil airfield, the bridges into Nasiriyah and the approaches to Basra, Brooks said.
Coalition forces have taken some 2,000 prisoners, and Abizaid promised the Red Cross will be allowed to visit them soon. He said the military is not seeing the same number of mass surrenders because most of the Iraqi soldiers are abandoning their positions but not turning themselves in.
"Here in the areas that we've been encountering regular Iraqi forces, by far the majority of units have just melted away. We find a substantial amount of abandoned equipment on the field, and in the regular army there is clearly very, very little will to fight," he said.
Coalition forces have still not found an chemical, biological or nuclear weapons or Scud missiles.
"Suffice it to say that we continue to look, but so far we haven't found any conclusive evidence. We are confident that we will find it," Abizaid said.
He said the United States believes Republican Guard forces at Al Kut have chemical weapons.
In northern Iraq, battle damage reconnaisance photos reviewed by UPI show an Ansar al Islam camp was almost completely destroyed by a Tomahawk cruise missile barrage on Saturday. Before and after photos showed at least 17 bomb craters and destroyed buildings.
Ansar al Islam is a militant Islamic group the United States government believes to be tied to al Qaida.
Fleet clearance diving teams and explosive ordnance disposal teams were clearing mines from the port at Umm Qasr and in the Al Abdullah waterway. Once it is safe, shipments of humanitarian aid will move in and begin distributing food, water and medical supplies. President George W. Bush said Sunday at the White House he expected "massive" amounts of aid to be delivered starting in the next 36 hours.
The 4th Infantry Divisions' tanks and armored vehicles are on ships now making their way south from the Mediterranean to the Red Sea and the Persian Gulf, having been denied entry into Turkey.
"I think it's a prudent measure to move it to the south because it's clear that in the near term, we would not be able to get the division and its equipment into the north in a timely manner as a result of various negotiations with Turkey," Abizaid said.
The United States does have overflight rights in Turkey, he noted.
An American sergeant with the 101st Airborne, Sgt. Asan Akbar, has been detained as a suspect in a grenade attack that killed one and injured 15 at a U.S. base, Camp Pennsylvania, in northern Kuwait. A spokesman at Fort Campbell, Ky., home of the division, said Akbar was known to have "an attitude problem."
Notable deaths of 2014 [PHOTOS]
Iraq seeks thousands of tank rounds