BAGHDAD, Dec. 22 -- Investigators believe a suicide bomber penetrated security at a U.S. military base in the northern Iraqi city of Mosul and detonated an explosive Tuesday that killed 22 people, including 14 U.S. service members, Gen. Richard B. Myers, chairman of the Joint Chiefs of Staff, said Wednesday. The attack, which also wounded 69, was the deadliest on an American installation since the beginning of the war in March 2003.
"We have had a suicide bomber apparently strap something to his body -- apparently a 'him' -- and go into a dining hall," Myers said at a news conference at the Pentagon. "We know how difficult this is, to prevent . . . people bent on suicide and stopping them."
An unidentified casualty from the attack on Forward Operating Base Marez near Mosul, is taken to an ambulance at the Ramstein Air Base in southern Germany. The attack killed 22 people, including 14 U.S. service members.
(Michael Probst -- AP)
The Post's Thomas E. Ricks discusses the attack on the U.S. military base and insurgent tactics in Iraq.
The preliminary finding by military and FBI investigators reinforced a claim posted on a Web site by a radical Iraqi group, Ansar al-Sunna, that one of its members had carried out a suicide attack. The group's statement, which appeared hours after the attack, boasted of a strike on "a restaurant for the blaspheming occupation forces."
The attack represented a startling breach of security at a U.S. base. "Force protection," the military phrase for keeping troops safe, has been an overarching priority for the military since devastating truck bomb attacks killed scores of Marines and soldiers massed in high-rise apartment buildings in Lebanon in 1983 and Saudi Arabia in 1996.
Tuesday's massive explosion, which sent a fireball through the canvas roof of the cavernous mess hall as several hundred soldiers sat down to lunch, was initially assumed to have been caused by mortar or rocket fire, which are frequently used to attack U.S. military bases in Iraq. But soldiers scrambling through the debris at Forward Operating Base Marez saw no jagged remnants typical of artillery shells.
Instead, witnesses said chairs and tables in the hall contained the small, round holes left by ball bearings. Such material is recommended for bomb components in instructions for assembling suicide vests on Internet exchanges. ABC News reported that investigators recovered part of the bomber's torso and portions of a suicide vest.
"Evidence found at the site includes components normally associated with improvised explosive devices," the military said in a statement released after midnight in Baghdad. "There was no physical evidence of a rocket, mortar or other type of indirect fire weapon."
Tight security is routine at the dozens of U.S. bases in Iraq, with heavy berms or high walls surrounding regularly patrolled perimeters. U.S. firms contracted to feed the troops routinely employ citizens from third countries, such as the Philippines, but Iraqis come on base each day to fill temporary jobs and or do construction work, such as building the concrete and steel mess hall at Marez.
In another posting on the Internet, Ansar al-Sunna said the suicide bomber was a Mosul man who had worked at the base for four months and provided intelligence to the group. The group said the man detonated plastic explosives hidden under his clothes, according to the posting, which was also quoted by ABC.
Ansar al-Sunna, a successor to the radical Ansar al-Islam militia that battled U.S. and Kurdish troops in the north at the beginning of the war, is reportedly based in Mosul. Dominated by Kurds, the group asserted responsibility for two attacks in February in the northern city of Irbil. Those attacks killed more than 100 people when attackers detonated suicide belts at crowded receptions hosted by Kurdish political parties.
Myers, appearing at the news conference with Defense Secretary Donald H. Rumsfeld, said the attack was "the responsibility of the insurgents, the same insurgents who attacked on 9/11. The way you prevent this is to win the war on extremism."
The general pledged to improve security. After insurgents penetrated Baghdad's heavily fortified Green Zone in October, authorities encased additional land behind 12-foot concrete walls and stationed U.S. soldiers at rigorous checkpoints along roadways.
"I assure you that everything possible is being done to get to the bottom of what happened and to take the appropriate steps so we can prevent potential future attacks of this nature," Myers said.
Mosul was locked down the day after the blast. Some residents said insurgents had circulated warnings that the city would be unsafe. Normally crowded streets in the city of 1.8 million were all but empty, except for U.S. armored vehicles. The U.S. forces closed the five bridges that span the Tigris River, which essentially divides Mosul's Arab and Kurdish populations. Children and college students were sent home early, and merchants pulled down metal shutters on their shops.
Other residents scrambled indoors after seeing the U.S. patrols, which have been attacked daily since insurgents swarmed over much of the city last month and chased away the entire police force. News agencies reported that troops cordoned off neighborhoods favored by insurgents and carried out raids.
Meanwhile, U.S. forces continued an offensive against insurgent strongholds in what has been called Triangle of Death south of Baghdad. Marines announced the arrest of 44 suspects in the area Wednesday, bringing to 850 the number detained in the past five months; almost 600 of those suspects were subsequently imprisoned, the military said.
Ibrahim Jafari, a Shiite Muslim who serves as one of Iraq's two interim vice presidents, said that the U.S.-led campaign has improved security but that problems remain. "The situation is unstable yet in Latifiyah," Jafari said, referring to a town where attacks on motorists are frequent. "It got quiet for a while, but some attacks took place recently. They still attack some passersby. They set up their checkpoints."
The interim government, meanwhile, announced that 2,000 residents of Fallujah would be allowed to return to their homes beginning Thursday. A U.S. offensive last month in the city, which is 35 miles west of Baghdad, reclaimed it from Iraqi insurgents and foreign fighters who had held it for six months.
"Insurgents are desperate to create the perception that elections are not possible," U.S. Gen. George W. Casey Jr., who commands the multinational force in Iraq, said in a statement. Nationwide elections are scheduled for Jan. 30. "We will not allow terrorist violence to stop progress toward elections."
The military reported that of the 22 people killed in the Mosul attack, 14 were U.S. service members, four were American civilians working as contractors on the base and three were members of the Iraqi security forces also living on the base. Another victim was described as an "unidentified non-U.S. person." It was not clear whether that person was assumed to be the attacker.
Special correspondents Ruaa Ahmed in Mosul and Bassam Sebti contributed to this report.