The bomber is seen dressed in black with a mask and wearing an explosives belt. The U.S. military has said the bomber may have been wearing an Iraqi security forces uniform when he slipped into a dining tent on the base and detonated his explosives.
Meanwhile, Iraq's top general on Sunday rejected President Bush's criticism that some Iraqi government troops were unwilling to fight insurgents and have deserted the battlefield, saying the president had been misinformed.
In an interview with The Associated Press, Gen. Babaker B. Shawkat Zebari also said that the man who carried out Tuesday's suicide attack in Mosul — in which 22 people died — was not a member of the Iraqi security forces.
The bombing, which was the deadliest attack on a U.S. base in Iraq, highlighted that the anti-U.S. insurgency has not diminished even after American offenses last month. A day before the attack, following a string of deadly suicide bombings in southern Iraq, Mr. Bush made a sobering assessment and criticized the performance of Iraqi troops.
"There have been some cases where, when the heat got on, they left the battlefield — that is unacceptable," President Bush said at a Dec. 20 press conference.
Asked about Mr. Bush's comments, Zebari told AP: "I think the president received misleading information."
Also Sunday, a roadside bomb hit a U.S. convoy in Mosul, setting a supply truck and wounding three U.S. soldiers, the military said.
Production of armored Humvees has been stepped up to better protect U.S. soldiers in Iraq from roadside bombs, but CBS News Correspondent Cami McCormick reports there's also a lot of effort going into new "techniques" to disable so-called IEDs (improvised Explosive Devices).
Chief Warrant Officer Kerry Fryer and his team can be on the move within ten minutes of a reported roadside bomb. They are an explosive ordnance disposal team, and find 90 percent of all the devices they find are constructed using cordless phones.
"The long-range cordless phone is their IED receiver of choice," Fryer said.
Insurgents use the phone base to activate their bombs. Marines are better protected in armored Humvees, but they're increasingly using electronic devices to block the phone's signals. And that provides the best protection of all.
Zebari, Iraq's only four-star general, insisted none of his troops had deserted from combat. But he acknowledged that some recruits undergoing training had quit after being told they would be posted to the restive city of Fallujah, which was taken in a U.S.-led assault in November.
"Not a single soldier ran away from the battlefield (in Fallujah). It was not a difficult battle. Fallujah was cleaned and the number of our martyrs (fatalities) was only seven." Zebari said.
Zebari said it was possible the bomber in the Mosul blast was wearing an Iraqi uniform, noting that such uniforms are sold in markets. "It is not difficult for a person to wear one," he said.
"Certainly (the suicide bomber) was not a member of the National Guards because all of our men stationed in the base have been accounted for," he said.
Iraqi National Guards are also posted at the American base at Marez, just south of Mosul, Iraq's third-largest city, 225 miles northwest of Baghdad.
The attack killed 18 American servicemembers and civilians and three Iraqi guardsmen and one unidentified "non-U.S. person" and wounded 69 people, prompting a wide-ranging investigation into how he had penetrated the heavily guarded area.
In the interview at his heavily guarded headquarters in downtown Baghdad, Zebari said Iraqi forces are getting stronger every day and that he expected them to be capable of replacing the Americans within six months to a year.
"The insurgents are getting weaker. Hardly a day passes without detaining or killing dozens of them," he said.
Interim Prime Minister Ayad Allawi recently said the government commands almost 100,000 trained and combat-ready Iraqis, including police, national guard and army, and has accelerated the development of special forces and a counter-terrorist strike force.
Defense Secretary Donald H. Rumsfeld has said the number of trained Iraqi forces is going to increase by 45,000 by elections set for Jan. 30.
Zebari reiterated his claim that foreign fighters are still infiltrating into Iraq from Syria.
"I don't know if the (Syrian) government is closing its eyes or the terrorists are finding their ways to cross," Zebari said.
Zebari said six Arabs using forged Iraqi identity cards were detained near the Syrian border on Thursday. He said the men were detained with explosives in their possession.
Zebari's comments came a day after Najaf's police commander, Ghaleb al-Jazaeri, said police detained an Iraqi who confessed to receiving training in a camp in Syria under the supervision of a Syrian military officer. The man was apparently involved in a bombing in Najaf earlier this month that killed 54 people.
Syria on Sunday dismissed al-Jazaeri's statements as "baseless and nonobjective."
In Baghdad, masked gunmen assassinated a high-ranking Iraqi police officer, Col. Yassin Ibrahim Jawad, and wounded his two bodyguards, police said.