Here are details of some of the major attacks in Iraq in the past year:
Jan. 18, 2011 - A suicide bomber attacks Iraqi police recruits in Tikrit, killing 50 people and wounding over 100.
Jan. 20 - Two separate car bombs kill up to 45 pilgrims near Iraq's holy Shi'ite city of Kerbala ahead of the culmination of a major Shi'ite Muslim religious rite.
Jan. 27 - A car bomb at a wake in a Shi'ite part of Baghdad kills more than 35 people and wounds scores of others.
March 29 - At least 53 people are killed and 98 wounded when gunmen take hostages at a provincial council headquarters in Saddam Hussein's hometown of Tikrit, precipitating a battle with security forces who sweep in to end the siege.
Aug. 15 - A wave of attacks strike cities across Iraq, killing around 70 people and wounding more than 200 in the bloodiest day yet in 2011.
-- In the worst incident, a roadside bomb followed by a car bomb targeting police kills at least 37 people in Kut, 150 km (95 miles) southeast of Baghdad. Other deadly attacks took place in Tikrit, Najaf, Diyala and Kerbala.
Aug. 28 - A bomber wearing a cast on his arm blows himself up in the main hall of the Umm al-Qura mosque, an important Sunni religious site in Baghdad. At least 32 people are killed and 39 wounded.
-- Leaders of the Iraqi Islamic Party, a major Sunni political bloc, said Islamic State of Iraq (ISI), an affiliate al Qaeda, carried out the bombing to hit one of IIP's most prominent leaders, Sunni lawmaker Khalid al-Fihdawi.
Dec. 22 - More than 10 coordinated bombings strike Baghdad, killing at least 72 people, with around 200 wounded.
-- At least 18 people are killed when a suicide bomber detonated an ambulance he was driving near a government office in the Karrada district. More bombs explode in the central Alawi area, Shaab and Shula in the north, all mainly Shi'ite areas.
-- The Islamic State of Iraq, an umbrella group for al Qaeda-linked insurgents, later claims responsibility.
Jan. 5, 2012 - Four bombs in mainly Shi'ite Muslim areas of Baghdad kill at least 73 people.
-- The biggest attack was beside a police checkpoint west of Nassiriya in the south, where a suicide bomber targeting Shi'ite pilgrims killed 44 people and wounded 81.
Jan. 9 - Two car bombs kill at least 15 people and wound 52 in the capital.
Jan. 14 - A suicide bomber disguised as a policeman kills at least 32 people and wounds 100 more in an attack on Shi'ite pilgrims at a police checkpoint in Basra, southern Iraq. (Reporting by David Cutler, London Editorial Reference Unit)