Baghdad and other cities are rocked by bombs and shootings believed to have been aimed at security forces
At least 55 people have been killed across Iraq in attacks mostly aimed at security forces. Iraqi officials said insurgents were making "frantic attempts" to show civilians that their country was doomed to violence for years to come.
The apparently co-ordinated bombings and shootings unfolded over a few hours in Baghdad, where most of the deaths occurred, and 11 other cities. They struck government offices and restaurants, and one in the town of Musayyib exploded close to a primary school. At least 225 people were wounded.
If the insurgents' goal was to show Iraqis how precarious their situation is, it appeared to be working.
"What is happening today is not simple security violations. It is a huge security failure and disaster," said Ahmed al-Tamimi, who was working at an education ministry office a block away from a restaurant that was bombed in the Shia neighbourhood of Kazimiyah in northern Baghdad. He described a hellish scene of human flesh and pools of blood at the restaurant.
"We want to know: what were the thousands of policemen and soldiers in Baghdad doing today while the terrorists were roaming the city and spreading violence?" Tamimi said.
It was the latest of a series of large-scale attacks that insurgents have launched every few weeks since the last US troops left Iraq in mid-December at the end of a nearly nine-year war.
The interior ministry blamed al-Qaida insurgents for the violence.
"These attacks are part of frantic attempts by the terrorist groups to show that the security situation in Iraq will not ever be stable," the ministry said in a statement. "These attacks are part of al-Qaida efforts to deliver a message to its supporters that al-Qaida is still operating inside Iraq, and it has the ability to launch strikes inside the capital or other cities and towns."
No group immediately claimed responsibility for the latest attacks, but targeting security officials is a hallmark of al-Qaida. Such violence achieves two goals: undermining the public's confidence in the ability of their police officers and soldiers to protect them, and discouraging people from joining or helping the security forces.
The ongoing nature of the violence and the fact that insurgents are able to launch a variety of attacks over a wide territory in Iraq shows the country is still deeply unstable, despite government assurances that it could protect itself when American troops left in December.
The violence points to a dangerous gap in the abilities of the Iraqi security forces that had particularly worried the departing US military: their ability to gather intelligence on insurgent groups and stop them before they launch deadly attacks. Gathering information on militants and their networks was a key area in which the US military helped their Iraqi counterparts.
Shortly after the withdrawal, a major political crisis with sectarian undertones erupted when Shia-dominated authorities sought to arrest the Sunni vice-president, Tariq al-Hashemi, on allegations that he commandeered death squads targeting security forces and government officials. The fear has been that these renewed sectarian tensions may push Iraq back to the violence it saw during the height of the insurgency in 2006 and 2007.
The US embassy in Baghdad alluded to that history in a statement calling the terrorist attacks "heinous" acts that "tear at the fabric of Iraqi unity".
"We are confident the Iraqi people will remain firm in their desire to keep sectarian division at bay," the statement said.
Al-Qaida claimed responsibility for a similar strike on 5 January that killed 78 people and mostly targeted Shia pilgrims in Baghdad in the worst day of violence that had shaken Iraq in months.
A senior Iraqi defence intelligence official said Thursday's attacks appeared to have been planned for at least one month. He said they aimed to frighten diplomats away from attending the Arab League's annual summit, which is scheduled to be held in Baghdad in late March.
Similar fears were part of the reason the League meeting was cancelled in Baghdad last year. The defence official spoke on condition of anonymity because he was not authorised to release the information.
Nationwide, security forces appeared to be targeted in at least 14 separate attacks, including a drive-by shooting in Baghdad that killed six police officers at a checkpoint before dawn. Police patrols in the capital and beyond also were besieged by roadside bombs and, in once case, a suicide bomber who blew up his car outside a police station in the city of Baqouba, 35 miles (60km) north-east of Baghdad.
Iraq's police are generally considered to be the weakest element of the country's security forces, and 20 were killed earlier this week by a suicide bomber outside the Baghdad police academy in an attack that angry residents blamed on political feuding.
But the latest violence spilled on to commuters, restaurant patrons, passersby and schoolchildren as well.
In the single deadliest strike, a car bomb in Baghdad's downtown shopping district of Karradah killed nine people and wounded 26. The blast could be felt blocks away, shaking buildings and windows. Associated Press TV footage showed people walking away from the scene covered in blood.
In Musayyib, a car bomb parked on the street between a restaurant and an elementary school killed three people and wounded 75. Most of the injured were schoolchildren, said police and health officials.