BAGHDAD - A man in a wheelchair laden with explosives persuaded security guards Monday to push him into an Iraqi operations centre, where he blew himself up in an attack that killed the centre's deputy commander.
The infiltration, along with a U.S. report that insurgents used an adolescent to carry out a suicide attack against a mosque last week, was the latest indication that al Qaeda in Iraq is expanding its tactics to avoid detection before a bombing.
The Iraqi military indefinitely banned all motorcycles, bicycles and hand-pushed and horse-drawn carts from Baghdad's streets on Sunday, two days after a bomb hidden under a horse-drawn cart exploded downtown, killing three civilians.
That attack came exactly one month after a suicide bomber pushing an electric heater atop a cart packed with hidden explosives attacked a high school in Baqouba. And in an attack at a tribal gathering near Fallujah on Jan. 20, the bomber was a 15-year-old boy carrying a box of candy.
Women also have been used more frequently as bombers in recent months, including two with a history of psychiatric treatment who killed about 100 people at pet markets in Baghdad on Feb. 1.
It remains unclear if al Qaeda has begun using teenagers and women because it has been unable to recruit new insurgents or because they are more difficult to detect.
On Monday, the United States condemned al Qaeda in Iraq for carrying out a massacre against Shiite religious pilgrims and trying to wrench the country back to the brink of civil war.
The attacks come even as violence has plunged to its lowest level since the months following the 2003 invasion.
U.S. Embassy spokesman Philip Reeker said that while al Qaeda in Iraq has been "severely damaged," it remains a "dangerous threat."
About 100 Iraqis have been killed -- or their bodies found -- in the last two days, including at least 56 in a single blast. The attacks have mainly targeted the millions of Shiites engaged in a nationwide pilgrimage to a holy shrine in the southern city of Karbala, where ceremonies culminate Wednesday.
The city is the burial site of Imam Hussein, one of Shiite Islam's most revered figures. The ceremonies commemorate the end of the 40-day mourning period following the anniversary of his death.
Al Qaeda has also been targeting fellow Sunni Arabs who have taken up arms against the militants and joined so-called awakening councils, U.S.-backed former insurgents who began rising up against the brutality and strict codes of Islamic conduct al Qaeda was trying to impose on local populations.
Gunmen killed Sheik Khamis Ali al-Zobaie, a leader of the awakening council in the Dora neighborhood of southern Baghdad, and his son, said Mustafa Kamal al-Jubouri. He added that the sheik was a relative of Salam al-Zobaie, who served as deputy prime minister before he quit the government last year.
In the wheelchair attack, the man approached the main checkpoint to the operation room command in the city of Samarra and said he needed to see the commander to ask for help. Guards pushed him through.
He was referred to the deputy commander instead after he said he was unable to walk up the stairs to see the commander, who was on the second floor, according to police at the scene. Iraqi officials at the scene confirmed details of the attack. Both the officials and the police spoke on condition of anonymity because they were not authorized to release the information.
It was unknown whether the attacker really was wheelchair-bound or was using the wheelchair as a prop.
The U.S. military had no immediate reply when asked about the blast. In the past, some initial reports about insurgent attacks later proved exaggerated or incomplete.
Samarra, 60 miles north of Baghdad, is the site of the golden domed Askariya mosque -- a Shiite shrine that was bombed two years ago, sparking waves of sectarian violence.
The recent attacks on pilgrims demonstrate that despite thousands of troops on alert and warnings to travelers, insurgents can puncture the cordon around the human river of worshippers.
"This indiscriminate violence further reflects the nature of this enemy who will target even those practicing their religion in an effort to re-ignite sectarian strife in Iraq," the U.S. Embassy and coalition military command said in a joint statement.
The U.S. military announced that on Sunday they had arrested four suspected al Qaeda in Iraq leaders in Baghdad. The four were believed to be involved in numerous recent operations in the area, including attacks using suicide vests and cars.
"Capturing these four terrorists will have a significant impact on terrorist elements in Baghdad," said Brig. Gen. Mike Milano, the deputy commanding general Baghdad and the U.S. Army's 4th Infantry Division.
