Baghdad, Iraq ? The Mahdi Army didn’t guard Shiite pilgrims on the roads to and from the holy city of Karbala this year.

The Shiite militiamen waited in the wings under a deal that eased the way for U.S.-Iraqi security sweeps through Baghdad. But their absence had many pilgrims and other Shiites feeling like easier targets.

That sense of vulnerability was driven home Sunday when some 70 pilgrims came under attack after passing through the most dangerous stretch of Sunni-dominated territory on the way back from Karbala. The men and boys were celebrating their good fortune when one noticed a car racing far too fast, coming toward them from behind. The bomber barreled into their flatbed truck, setting off an explosion that killed at least 32 and wounded at least 24.

The attack rocked a neighborhood that is largely under tight Shiite control, a day after a bombing that killed 20 people in the Sadr City neighborhood where the Mahdi militia is based.

“I blame the government,” said Mustafa Moussawi, the pilgrim who saw the bomber. “They didn’t provide a safe route for us even though they knew we were targets for attack.”

Mahdi Army protection

Over the past two years, the Mahdi Army provided security – although they were unable to halt some deadly bombings and shootings – for the pilgrimage marking the end of 40 days mourning for the seventh century battlefield death of the Prophet Muhammad’s grandson. Shiites consider him the rightful heir of Islam’s leadership. Sunni Muslims do not.

The pact that kept the Mahdi Army off the streets this year apparently led to a decrease in execution-style slayings blamed on Shiite death squads. But bomb attacks continue – and each blast chips away at the public’s confidence that U.S. troops and their Iraqi partners can protect them.

After a week in which some 340 people, mostly Shiite pilgrims en route to Karbala, were killed in sectarian attacks, Sunday’s attack once again demonstrated the limitations of the U.S.-led crackdown seeking to restore order in the capital.

The attacks put pressure on the Shiite militia to respond, perhaps part of the attackers’ strategy of drawing Shiite forces back onto the streets and into confrontation with the Americans.

Outside the capital Sunday, Sunni extremists attacked Shiites and set about 30 houses on fire in villages around Muqdadiyah, 60 miles northeast of Baghdad, forcing dozens of families to flee, local officials and witnesses said.

Shortly before the pilgrims’ truck was attacked in Baghdad, a bomb-rigged car in central Baghdad killed at least five pilgrims and injured six. In another part of the city, a suicide bomber detonated a belt packed with metal fragments inside a minibus heading to a mostly Shiite area, killing at least 10 people and wounding five.

Iraqi army soldiers patrol as a man prays on the street in Baghdad, Iraq, on Sunday. A suicide car bomber rammed a truck carrying Shiite pilgrims returning from a major religious commemoration Sunday, killing at least 32 people a day after Iraqi leaders warned sectarian violence could eventually spread around the region.

Leaders’ conference

On Saturday, Iraq’s prime minister, Nouri al-Maliki, opened a conference of neighboring nations and world powers with a warning that Iraq’s sectarian strife could spread across the region.

The one-day meeting was highlighted by rare direct exchanges between Iran and the United States – which reportedly grew testy in the closed-door session with other envoys.

Iran pressed for a timetable for a withdrawal of U.S.-led forces from Iraq, and the U.S. delegation reasserted claims that Shiite militia receive weapons and aid from Iranian sources.

But the gathering also ended with both sides leaving open the possibility of further contacts to discuss Iraq – where they share interests as Baghdad’s top allies.

Other developments

The U.S. military reported three soldiers killed Sunday. One was killed by a roadside bomb southwest of the capital, while another died in combat and the third was killed in an unspecified “noncombat incident” in northern Iraq, the military said.

In Salahuddin province northwest of Baghdad, Iraqi-led forces backed by U.S. warplanes staged raids against suspected insurgent training bases, including sites linked to anti-aircraft batteries, the U.S. military said. At least seven suspected insurgents were reported killed.

In the northern city of Mosul, a suicide bomber attacked the offices of the largest Sunni political group, said Mohammed Shakir al-Ghanam, a member of the Iraqi Islamic Party. Three guards were killed and two wounded, he said.

The reason for the attack was not immediately clear. The party is the only Sunni political movement with a national base.

Mosul, about 225 miles northwest of Baghdad, also has witnessed a rise in suspected Sunni insurgent attacks. Iraqi troops detained 12 suspected militants in the Mosul area in raids since Saturday, said an Iraqi commander, Brig. Gen. Mutaa al-Khazraji.

Brig. Gen. Dana Pittard, who commands U.S. units training Iraqi forces, said nearly 80 percent of Iraqi military divisions are under full local control, but getting the forces fully outfitted with “logistical support” – such as communications and state-of-the art equipment – “is going to take much more time.”

He also encouraged Iraqi government efforts to bring back some former military and security personnel from Saddam Hussein’s regime – who were part of wholesale dismissals to clear away members of his Baath party.

“It’s what a person’s talents and experience can bring to the situation,” said Pittard, who noted complaints that the past Baath purges “went way, way too far.”