A look at recent major attacks in Nigeria attributed to the radical Islamist sect known as Boko Haram:
_ Jan. 20: Boko Haram claims responsibility for a series of coordinated bombings and gun battles around the city of Kano that kill at least 143 people.
_ Dec. 25, 2011: Boko Haram claims responsibility for an attack on a Catholic church in Madalla near Nigeria's capital and assaults elsewhere in the country that kill at least 42 people.
_ Dec. 22-24, 2011: Sect members fight with police and military forces around the city of Damaturu, leaving at least 61 people dead.
_ Nov. 4, 2011: Sect members bomb government buildings and shoot their way through the city of Damaturu, killing more than 100 people, while bombs and a suicide attack in Maiduguri leave 4 dead.
_ Aug. 26, 2011: A sect member detonates a car loaded with explosives at the United Nations headquarters in Nigeria's capital Abuja, killing 25 people and wounding more than 100 others.
_ June 16, 2011: A car loaded with explosives detonates at the federal police headquarters in Abuja, killing at least two people. Police first call the attack a suicide bombing, but later deny it.
_ April 9, 2011: Gunmen from the sect set fire to the Maiduguri International Hotel and kill a politician ahead of local elections.
_ April 8, 2011: A bomb allegedly planted by the sect explodes at an election office in Suleja in Niger state, killing 16 people.
_ Jan. 28, 2011: Gunmen with the sect shoot and kill the leading candidate for governor in Borno state along with six others in his entourage.
_ Dec. 31, 2010: A bomb allegedly planted by the sect explodes at a crowded and popular outdoor beer garden at a military barracks in Abuja, killing at least four people.
_ Dec. 24, 2010: A series of bombs allegedly planted by the group explode in the central Nigerian city of Jos, killing as many as 80 people.
_ Sept. 7, 2010: Gunmen with the sect free about 700 inmates from a Bauchi federal prison.
_ July 2009: About 700 people die after sect members riot and a security crackdown hits Maiduguri, the sect's spiritual home.