The new Iraqi government was settling in. The Americans sounded ready to pull out their troops as promised. Even the Iraqi soccer team was winning. The winter days in Baghdad were sunny with a whiff of hope in the air. Then came major suicide bombings on three straight days this week. 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 said Friday in the city of Karbala. Karbala, 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. Wednesday, another suicide bomber crashed the ambulance he was driving through the gates of a police headquarters in Baqouba, 35 miles (60 kilometers) 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, 80 miles (130 kilometers) 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. 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.” No group has yet claimed responsibility for the bombings, which bear the hallmarks of Al-Qaeda or its allied militant organizations. The attacks could signal Al-Qaeda's response to the recent displays of Shiite dominance in Iraq –including this month's surprise return of anti-American cleric Muqtada Al-Sadr – or simply a reminder of its might. Hakim Al-Zamili, a lawmaker in Al-Sadr's political movement, said the fiery cleric's supporters were unlikely to wait for the government to fix the security crisis. His remarks were a veiled threat to reassemble the Mahdi Army, Al-Sadr's militant wing. “We have reached a stage where we will not stand for any more attacks,” Al-Zamili said in an interview Friday. Al-Zamili maintained Al-Sadr's offer to register the Mahdi Army with Iraqi forces and help plug security gaps, but said the government continues to rebuff it. “The government does not really trust us,” he said. The United States has long feared that the return of the Mahdi Army – especially if unchecked – will lead to the tit-for-tat killings that nearly brought Iraq into civil war from 2005 to 2008. Such a specter could force Baghdad to negotiate a new security agreement with Washington to keep US forces in Iraq beyond their Dec. 31 departure deadline. Senior officials at the US Embassy in Baghdad continue to say they plan for the military to leave at the end of the year. But the Obama administration has left the door open for some troops to remain if Iraq's government asks for them. 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.”