The bombings, which killed more than 120 people and wounded hundreds, laid bare Iraq's reality: Despite many gains since it teetered on the brink of civil war, the nation remains unstable with occasional bursts of large-scale attacks.

“There is maliciousness and criminal schemes to destabilize Iraq, to create sedition among Iraqis so that the chaos prevails,” Sheik Abdul-Mahdi Al-Karbalaie told thousands of worshippers during Friday prayers at the Imam Hussein shrine in the holy city of Karbala.

Al-Karbalaie is a top representative of the revered cleric Grand Ayatollah Ali Al-Sistani. He urged Iraqis to unite against “such criminal schemes.” Karbala, some 90 km south of Baghdad, was the destination of pilgrims who were among those killed in a triple suicide bombing at highway checkpoints Thursday that left 56 dead and more than 180 wounded.

On Wednesday, another suicide bomber crashed the ambulance he was driving through the gates of a police headquarters in Baqouba, 60 km northeast of the capital, killing seven people and wounding 67.

And at least 65 people died and 150 people were hurt Tuesday when a suicide bomber set off his explosives-packed vest in a crowd of police recruits in Saddam Hussein's hometown of Tikrit, 130 km north of Baghdad.

The bombings abruptly ended a month of relative calm across Iraq. Until now, the newly designated government, its leaders seated in December, largely were focused on the prospect of running the country without the help of the American military when its 47,000 troops are scheduled to leave at the end of the year.

Iraqis themselves have been fixated on woes like electricity shortages during the chilly winter and, for fun, the country's winning soccer team advancing to the quarterfinals in the Asian Cup. And US officials optimistically predicted Iraq may have turned the corner after a mid-January visit by Vice President Joe Biden came off without the Green Zone being shelled with rockets and mortars.

Now, in the bombings' wake, Iraqi officials and foreign diplomats alike are again sounding the alarm.

UN envoy to Iraq Ad Melkert “is deeply concerned at the continuation of targeted attacks,” according to a statement from his office. Iraqi President Jalal Talabani said the Karbala bombings aimed “at provoking sedition and spreading fear and turmoil.” “Iraq has serious problems that need to be addressed,” said Joost Hiltermann from the International Crisis Group.

“And if any international community takes its eye off the ball, then the security situation could easily deteriorate, as the groups that carry out these attacks are still around and obviously capable of penetrating security cordons.”

Baghdad political analyst Kadhum Al-Muqdadi said insurgents are taking advantage of Iraq's rudderless forces as Prime Minister Nuri Al-Maliki waits to appoint his Cabinet's national security, defense and interior police ministers.

The prime minister, who says he wants more time to select leaders who are apolitical, controls all security forces until those Cabinet posts are filled.

Al-Muqdadi said attacks show the insurgents are far from being cowed.

“It is a message that they have not been paralyzed yet,” he said. “And they are still able to cause major blows in many directions day after day.”