ERBIL, Iraq -- A suicide car bomber wearing a police uniform killed at least 15 traffic officers and wounded 100 others early yesterday during roll call at a police headquarters in this oil-rich northern Kurdish city.
The bombing was the largest in a day of violence that saw at least 37 people killed, mostly Iraqi police and soldiers. One US soldier was killed by a roadside bomb in northern Iraq.
The Erbil attack was the latest in a relentless series of explosions that have killed nearly 1,200 people in less than two months. On Sunday, a suicide bomber walked into a Baghdad kebab restaurant popular with police officers and blew himself up, killing 23 people, including seven officers.
''Most of the attacks targeting the Iraqi security forces, including the police, are launched by Islamic fundamentalists," said Sabah Kadhim, an Interior Ministry spokesman. ''Iraq has become the center of global terrorism, and those groups' attacks are aiming to create a sectarian crisis. Their main aim is to keep the country in chaos."
In Washington yesterday, President Bush defended his polices on Iraq and the war on terrorism, saying the Iraqi conflict will be won despite the efforts of ''cold-hearted killers."
''I understand we have troops in harm's way," the president said during a White House news conference. ''We will complete the mission, and the world will be better off for it."
In an audiotaped message last month, Jordanian-born Abu Musab al-Zarqawi, who leads Al Qaeda in Iraq, purportedly gave his approval to the killing of fellow Muslims and civilians collaborating with the Shi'ite-led government and the United States.
Extremists have in recent weeks mostly targeted the Iraqi security forces at the forefront of government counterinsurgency operations, both in an effort to shatter their morale and prevent recruits from signing up.
Sunni Arabs make up the core of Iraq's insurgency, and the minority has felt politically embittered by the rise of the Shi'ites and the Kurds -- two communities that account for about 80 percent of the country's estimated 26 million people. Many Sunni Arabs boycotted January's historic elections.
''Terrorist groups try to stand against Iraq's political process," Erbil's governor, Nowzat Hadi, told reporters. ''Terrorists are trying to harm the Kurdish region because it is a secure place and because Erbil represents the political center of Kurdistan."
Erbil and nearby Sulaimaniyah are two key cities in Iraq's northern Kurdish region, which has enjoyed autonomous rule since 1991. The area has been largely sheltered from the violence that has been wracking the remainder of Iraq, but has seen several major bombings attributed to militant groups.
The number of insurgent attacks has escalated since Prime Minister Ibrahim al-Jaafari announced his Shi'ite-led government April 28.
Some extremists have started to threaten fellow Sunni Arabs because some minority leaders have expressed a readiness to join the political process.
Sunni Arabs submitted a list of 15 candidates for a Shi'ite-dominated committee drafting Iraq's constitution Sunday, but were having second thoughts yesterday about a demand made by legislators that the group be endorsed by representatives of the entire community. The snag could delay the constitutional process, further eroding the little time left for the charter to be drafted by mid-August.
A US-led offensive dubbed Operation Spear ended yesterday. It was launched last week with 1,000 Marines and Iraqi soldiers in western Anbar Province to ebb the flow of foreign fighters entering from Syria.
The four-day campaign in the city of Karabilah, 200 miles west of Baghdad, killed about 60 insurgents. One Marine also died.
''The operation was very successful because we cleaned out some insurgent weapons caches, we found evidence of lots of foreign fighter involvement, and we fully integrated with the Iraqi security forces," said Marine Lieutenant Colonel Tim Mundy of Waynesville, N.C., who commanded the operation.
Intelligence officials contend Anbar Province is a portal for extremist groups, including Al Qaeda in Iraq, to smuggle in foreign fighters.
In other violence yesterday:
A band of insurgents launched a bold assault on a Baghdad police station, killing at least eight police officers and an 8-month-old, police said. At least 23 people were wounded. The attack included two car suicide bombs, mortars, rocket-propelled grenades, and small-arms fire, police said.
A suicide car bomber ripped through a convoy in Halabja that was carrying a Kurdish town's security director, killing him and three bodyguards.
A suicide car bomber rammed into an Iraqi Army checkpoint in Kirkuk, killing five soldiers and wounding three.
Millions of Baghdad residents went without city water for a second day yesterday after a rocket attack on a pipeline, and city officials said the problem could extend into a third day. The mayor's office said repairs would be completed by late today. Insurgents have often hit infrastructure in a bid to destabilize the government.