Baghdad, Iraq ? A suicide bomber strapped with explosives killed nearly two dozen people at a busy downtown restaurant frequented by Iraqi police, topping a series of bloody attacks Sunday that killed at least 36 Iraqis nationwide, including 12 members of the U.S.-trained security forces.

A U.S. Marine was killed in fighting in western Iraq, where the military has launched offensives aimed at rooting out insurgent strongholds in the country’s rural Sunni Arab enclaves. The Marine Corps said Sudanese and Saudi Arabians were among at least 39 insurgents killed in fighting near Karabilah, a town near the border with Syria.

The deaths in Baghdad followed assurances by U.S. and Iraqi military officials that an Iraqi-led offensive, Operation Lightning, was controlling violence in the capital.

Pedestrians killed

The bombing of the Ibn Zanbur restaurant killed at least 23 Iraqis, including seven police officers, and injured 16 Iraqi police officers and 20 civilians. The popular eatery was located less than 400 yards away from the main pedestrian entrance to the U.S.-protected Green Zone.

Sunni Arab insurgents have been waging a guerrilla war against U.S.-led forces and the transitional Iraqi government, led mainly by Shiites and Kurds. Iraq’s nascent security forces have born the brunt of a bombing and assassination campaign.

An Iraqi soldier steps through the wreckage of a Baghdad, Iraq, restaurant that was blown up by a suicide attacker Sunday. A suicide bomber wearing a vest laden with explosives blew himself up inside the popular Baghdad kebab restaurant, killing at least two dozen people and injuring 36 others, just outside the main gate of the heavily fortified Green Zone.

But most of those killed and injured at the restaurant Sunday afternoon were pedestrians and diners, including a beggar who frequented the street.

“I know we are targets,” said Ali Abbas, 35, an off-duty police officer who witnessed the explosion, which occurred at 2:30 p.m., from several hundred yards away. “But there were innocent pedestrians killed who had nothing to do with all of this.”

Police in white SUVs, firefighters in emergency vehicles and U.S. soldiers in Humvees quickly arrived and secured the scene. Residents and shopkeepers began loading the dying and wounded into police cars, which whisked them off to area hospitals. Arriving police officers and Iraqi soldiers fired automatic weapons into the air, sending women and children in nearby neighborhoods cowering for cover.

Other bombings

Earlier, three Iraqi civilians were killed by a car bomb that exploded as a police patrol passed another section of Baghdad. Thirty Iraqis were wounded, a U.S. Army news release said.

Another car bomb aimed at a patrol in the Kadhemiya district of Baghdad killed at least four Iraqi civilians, including a young girl, a Ministry of Interior source said.

Outside the capital, a car bomb exploded at the entrance of a military base in Saddam Hussein’s hometown of Tikrit, killing seven Iraqis, including five members of the Iraqi army.

Troops spread thin

In volatile Al Anbar province, where the Sunni Arab-led insurgency is strong, Marines battled on several fronts, including Karabilah, near the Syrian border, the focus of an attack known as Operation Spear. But U.S. forces are stretched thin in the vast expanses of Al Anbar, and guerrillas have been quick to return once U.S. forces leave.

“We cannot defend everywhere: They will attempt to fill the vacuum,” said Marine Col. Bob Chase, who was in Ramadi, the provincial capital. “Since we cannot defend every square inch of border, we will come in intermittently, when they least expect it.”

Elsewhere, Chase said a firefight southwest of Fallujah early Sunday left 15 insurgents dead and 24 captured. The insurgents were part of a cell dedicated to making roadside bombs, he said.

‘Long road ahead’

Appearing on several American news programs Sunday morning, Secretary of State Condoleezza Rice seemed to distance herself from recent comments by Vice President Dick Cheney that the Iraqi insurgency was in its “last throes.”

She avoided direct answers to questions on the topic, instead saying that the insurgency would eventually be defeated by a combination of military and political successes by the Iraqis.

“The Iraqi people are not supportive of these insurgents,” Rice said on “Fox News Sunday.” “Yes, they can continue to cause carnage. But what they’re losing is that they’re losing the Iraqi people. And that’s the most important loss that you can inflict upon an insurgency.”

Iraqi forces “have a long road ahead of them. They are not ready to stand on their own right now,” Rice said on ABC’s “This Week.” “But Iraqi forces, when they are trained, are in some ways going to be better at some of these functions than coalition forces.”

Reconstruction conference

Meanwhile, the Iraqi government made progress on the diplomatic front Sunday, preparing for a high-profile Brussels, Belgium, conference on the country’s future and patching up ties with neighboring Kuwait.

Citing Iraq’s security challenges, wealthy European and Asian countries, as well as the United Nations, have mostly declined to participate in Iraqi reconstruction projects. But Iraqi diplomats have argued that donor nations can invest in Iraq’s relatively safe Shiite south or Kurdish north.

Foreign Minister Hoshyar Zebari said Sunday that he would encourage countries that had promised aid to pay up at the conference, which begins Wednesday. “The conference aim is to achieve the biggest amount of international participation in order to stabilize Iraq,” he told reporters. “Iraq is considered a balancing factor for the neighboring countries, America and Europe.”

Prime Minister Ibrahim al-Jaafari headed a high-level delegation that arrived Sunday in Kuwait on an Iraqi Airways flight. It was his first visit as prime minister to the country that Saddam’s military occupied in 1990, leading to the first U.S.-led military confrontation with Iraq in early 1991. According to a news release, Kuwait is lending Iraq $60 million for hospital and school reconstruction and $500 million for other projects.