A string of bombings in northern Iraq and Baghdad that has killed at least 112 people in the last several days, including 60 on Monday, has raised fears that insurgent groups are embarking on a sustained attempt to kindle ethnic and sectarian warfare.
The toll since Friday represents the worst surge of violence since U.S. troops handed over security in urban areas to Iraqi security forces on June 30.
The attacks serve as a reminder that although the U.S. military says it is on track to complete the withdrawal of U.S. combat forces from Iraq by next August, the potential for fresh conflict between Arabs and Kurds in the north, and Sunnis and Shiites elsewhere, remains very real.
The violence in and around the northern city of Mosul is the biggest concern. Mosul is a stronghold for the militant group Al Qaeda in Iraq and insurgents loyal to the former Baath Party, both of which U.S. commanders accuse of stoking ethnic and sectarian tensions to provoke a civil war in what remains the most volatile part of the country.
Gen. Ray T. Odierno, commander of U.S. troops in Iraq, recently identified Arab-Kurdish tensions as "the No. 1 driver of instability" in the country.
Prime Minister Nouri Maliki told a gathering of Iraqi army commanders in Baghdad on Monday that insurgents were attempting to undermine confidence in the ability of Iraq's security forces, and warned that more violence could be expected ahead of national elections due in January.
"They are trying through any means to give the impression that the political process is not stable," he said. "Yet through your efforts and determination . . . they won't find any safe haven from which to plan and execute their operations."
The bloodiest attack Monday came before dawn about 13 miles east of Mosul in a village that is home to members of Iraq's tiny Shabak religious minority. Two massive truck bombs detonated on either end of the main street in Khazna about 4:30 a.m., killing at least 35 people, wounding 180 and leveling more than 30 houses.
Many people had been sleeping in the open on their roofs because of the intense summer heat, and at the Jamhouriya hospital in Mosul, survivors described how their homes collapsed beneath them as they were startled awake by the massive explosions.
"There were 12 people living in my sister's house and not one is left alive," cried Mahasin Haider, 45. "They uncovered some of the bodies and the rest are still buried in the rubble."
Khazna lies in an area controlled by the Kurdish peshmerga militia and, like a similar attack Friday against a minority Shiite Turkmen mosque north of Mosul, this one seemed aimed at intensifying conflict between Kurds and Arabs over the land.
"Our initial assessment is that one or more insurgent groups are behind the attack," said Maj. Derrick Cheng, a spokesman for U.S. forces in northern Iraq. "These groups are attempting to exploit or create ethnic and sectarian fault lines."
At stake is a swath of territory in the northern province of Nineveh that is claimed by Kurds and Arabs and under Kurdish control. Kurds want a referendum to be held among the mostly Kurdish population to cement claims that the land should remain with the semiautonomous Kurdistan region.
But many Arabs oppose Kurdish claims, and since the victory of the hard-line Arab nationalist Hadba Party in January's provincial elections, the Nineveh government has been pushing for the Iraqi army to be deployed in the Kurdish-controlled areas, putting it at odds with Kurdish leaders.
"It's the political disputes between the Hadba bloc and the Kurdish bloc that encourage the terrorists to carry out such operations in the province of Nineveh," Shabak lawmaker Hunain Qaddo told Iraqi state television.
After an emergency closed-door meeting, the Hadba- controlled provincial council issued a statement calling on the Iraqi army and police to be immediately deployed in Kurdish-controlled areas in place of the peshmerga in order "to control all the soil of the province."
Kurds have long boasted that the areas under their control are calmer than any other part of Iraq, and Khasro Goran, a prominent Kurdish official in Mosul, rejected the call for Iraqi troops. "Some people, whether Al Qaeda or loyalist former Baathists, are trying to create a civil war in this province," he said.
Caught in the middle are the region's ethnic and religious minorities, including Christians, Yazidis, Turkmens and Shabaks. Many minorities chafe under Kurdish rule, but they lack political clout.
The target of Monday's attack, Shabaks, are a small ethnic and religious group that has its own language and is neither Sunni nor Shiite, though a majority identify more closely with Shiites than Sunnis and have aligned themselves with Maliki's government.
They have another holy book in addition to the Koran, and they permit alcohol and emphasize confession, in common with Christianity.
Maliki has also previously called for Iraqi troops to be deployed across the nation, putting him at odds with the Kurdish leadership.
But he has recently reached out to the Kurds with a visit Aug. 2 to Kurdish President Massoud Barzani, and the recent attacks on Shiite minorities may be an attempt to thwart their fledgling rapprochement, Goran said. "They're trying to create problems between the Kurdish regional government and the central government," he said.
Meanwhile, in Baghdad, 11 bombings, mostly against Shiite targets, killed 25 people and injured dozens more in a surge of violence in the capital that seemed aimed at stoking Sunni-Shiite tensions.
In the worst of those attacks, at 6:30 a.m., two car bombs exploded minutes apart at two locations where day laborers gather to wait for work. The bombs killed 19 laborers and wounded 83 in Shurta and Amel, two Shiite neighborhoods of mostly Sunni west Baghdad from which Sunnis had been purged during the 2005-07 sectarian fighting. Nine other smaller bombings scattered around the city killed six people and wounded 40.
U.S. Ambassador Christopher Hill and Odierno, the U.S. commander, issued a joint statement condemning the attacks, calling them "criminal acts of terrorism."
"Their sole intent," the statement read, "is to incite division within Iraqi society."
Times staff writers Caesar Ahmed and Saif Hameed in Baghdad and a special correspondent in Mosul contributed to this report.