A powerful bomb killed three American soldiers trying to clear explosives from a highway near Baghdad on Wednesday, and a suicide attacker blew himself up in a cafe northeast of the capital, killing 30 people and wounding dozens.
The deadly assaults occurred as Iraqi security forces struggled to protect more than 1 million Shiite pilgrims streaming toward the holy city of Karbala for annual religious rituals — and facing a string of attacks along the way that have claimed more than 150 lives in two days.
They included 22 people — 12 police commandos and 10 civilians — who died Wednesday in a car bombing at a checkpoint in southern Baghdad set up to protect pilgrims, the U.S. military said. An Iraqi TV cameraman working for a Shiite-owned station was among the civilian dead, his station said.
One American soldier was wounded in the attack on the bombing-clearing team on a major highway just north of the capital, the U.S. military said. The names of the victims were withheld until their families are notified.
American troops have stepped up efforts to clear and secure major highways around the capital as part of the Baghdad security crackdown, which began last month.
But the operation, which will eventually see an additional 17,000 U.S. combat troops in the capital, has so far failed to intimidate Sunni insurgents, who have retaliated with attacks outside the city, including those against Shiite pilgrims.
At least 13 U.S. troops have been killed in Iraq since Sunday, all of them in Sunni areas north and east of Baghdad. Nine Americans died Monday, the deadliest day for the U.S. military here in nearly a month.
The suicide attack took place near sunset at a popular cafe in Balad Ruz, 45 miles northeast of Baghdad, where Sunni extremists have been forcing Shiites to flee through a campaign of assassination and intimidation.
A senior police officer said dozens of people were gathered around the cafe enjoying mild, sunny weather when the attacker struck, killing 30 people and wounding 25. The officer spoke on condition of anonymity, fearing for his personal safety.
Iraqi security forces have been bracing for more trouble this weekend at the climax of Shiite religious rites marking the end of a 40-day mourning period for Imam Hussein, grandson of the Prophet Muhammad. Hussein's death in a 7th-century battle near Karbala cemented the schism between Sunnis and Shiites.
Hundreds of thousands of Shiite pilgrims were streaming by bus, car and foot into Karbala, 50 miles south of Baghdad, many of them marching behind banners affirming their reverence for Imam Hussein.
The targeted violence came a day afterexploded themselves among pilgrims lining up at a checkpoint, killing at least 120 people and wounding about 190, police and hospital officials said.
In other developments:
Local Gov. Aqeel al-Khazalie said 10,000 policeman were deployed in the city, with pilgrims undergoing multiple searches at checkpoints before they reach the two major shrines, the focus of the weekend rites.
"All the city's entrances have been secured, and I call upon the pilgrims to follow the instructions of the security forces and let them do the necessary searches," Iraq's minister of state for national security, Sherwan al-Waili, said in Karbala.
"Terrorists are adapting and improvising new ways of hurting people. Preparations have been made in hospitals to receive emergency cases," he said.
But the attacks have done little to discourage religious fervor among the Shiites, free to practice their rituals since the collapse of Sadddam Hussein's Sunni-led regime in 2003.
Abbas Ghatie Ali, a 32-year-old pilgrim walking from Baghdad to Karbala, tied a list of emergency contacts around his neck in case he was hurt along the way.
"I'm wearing this card to identify me if I'm killed during the journey to Karbala," Ali said. He said he would defy threats by Sunni extremists because Shiites are "the majority and will defend our ideology and doctrine."
Another pilgrim, Khadija Tawfek Mouhsin, said his brother was killed last year on a march to Karbala but he was determined to make the trip himself. "The terrorists give us the chance to go to paradise," he said.
During the past two years, the Mahdi Army militia of radical Shiite cleric Muqtada al-Sadr watched over pilgrimages to Karbala. This year, the militia bowed to government pressure and put aside their arms to avoid any confrontation with U.S.-led forces during the Baghdad security crackdown.
With the militia on the sidelines, Shiite leaders have expressed anger that the Shiite-led government security force had failed to protect the marchers.
Attacks against pilgrims have also sharpened sectarian tensions at a time when U.S. officials had hoped the Baghdad security operation would encourage Shiite, Sunni and Shiite leaders to come together in power-sharing agreements to end the crisis.
Instead, new strains have emerged, not only between the rival Islamic sects but within the dominate Shiite political bloc itself.
On Wednesday, the Fadhila party, which holds 15 seats in parliament, announced it was withdrawing from the Shiite alliance and serve as an independent bloc.
The reason for Fadhila's decision was unclear, but the party, which controls the provincial administration in Basra, appeared to be positioning itself to align with other sectarian factions at a time of growing disappointment over Prime Minister Nouri al-Maliki's government.