Pakistan has been gripped by an insurgency for more than a decade, an internal war with the Taliban and other radical groups that has killed tens of thousands of civilians and security personnel since successive governments in Islamabad joined the United States and its allies in a war against Al-Qaida, the Taliban and Islamic extremism in 2001.
Tuesday's school attack, which took the lives of at least 126 people, was among the worst in a decade, and follows last summer's government offensive against extremist strongholds that came in response to a Taliban attack on Karachi international airport.
A look at some of the major attacks in Pakistan in recent years:
— November 2: Taliban suicide bomber kills 60 in attack on a paramilitary checkpoint close to the Wagah border crossing with India.
— June 9: Ten gunmen disguised as police guards attack a terminal at Pakistan's busiest airport with machine guns and a rocket launcher, killing 13 people during a five-hour siege.
— June 8: A suicide bomber in the country's southwest killed at least 23 Shiite pilgrims returning from Iran.
—September 22: A twin suicide bomb blast in a Peshawar church kills at least 85 people.
—August 17: Heavily armed Taliban fighters blast their way into a Pakistani air force base, leaving two security officers and nine insurgents dead.
—June 22: 10 Foreign climbers killed by militants on Nanga Parbat, ninth highest mountain in world.
—March 3: Explosion in Karachi kills 45 Shiites outside a mosque.
— January 10: Bombing in Shiite area of southern city of Quetta kills 81 people, wounds 120.
— November 22: A Taliban suicide bomber struck a Shiite Muslim procession in the city of Rawalpindi, near Pakistan's capital, killing 23 people.
— January 5: Taliban shoot and kill 15 Pakistani frontier police after holding them hostage for more than a year.
— September 20: Militants kill at least 26 Shiites on a bus near the southern city of Quetta.
— May 23: Pakistani commandos recapture a major naval base from Taliban attackers who struck to avenge the killing of Osama bin Laden in a U.S. raid. Militants destroyed two U.S.-supplied surveillance aircraft and killed at least 10 personnel.
— May 13: A pair of Taliban suicide bombers attacks paramilitary police recruits in Shabqadar, killing 80, also in retaliation for bin Laden's killing.
— November 5: A suicide bomber strikes a Sunni mosque in Darra Adam Khel in northwestern Pakistan, killing at least 67 during Friday prayers.
— Sept. 1: A triple Taliban suicide attack on a Shiite Muslim procession kills 65 in the southwestern city of Quetta.
— July 9: Two suicide bombers kills 102 people in the Mohmand tribal region.
— July 2: Suicide bombers attack Pakistan's most revered Sufi shrine in the eastern city of Lahore, killing 47 people.
— May 29: Two militant squads armed with hand grenades, suicide vests and assault rifles attack two mosques of the Ahmadi minority sect in Lahore, killing 97.
— March 13: Two suicide bombers targeting army vehicles in Lahore kill more than 55 people.
— January 1: A suicide bomber drives a truckload of explosives into a volleyball field in Lakki Marwat district in the northwest, killing at least 97 people.
— December 28: Bomb blast kills at least 44 at a Shiite procession in the southern city of Karachi.
— December 7: Two bombs kill 48 at a market in the eastern city of Lahore, while a suicide bomber kills 10 people outside a Peshawar courthouse.
— October 9: A suicide car bomber hits a busy market area in Peshawar, killing 53.
— May 27: A suicide car bomber targets police and intelligence offices in the eastern city of Lahore, killing about 30 people.
— March 27: A suicide bomber demolishes a packed mosque near the northwestern town of Jamrud, killing about 50.
— March 3: Gunmen attack the Sri Lankan national cricket team in Lahore, wounding several of the players and killing six policemen and a driver.
— September 20: A suicide bomber devastates the Marriott Hotel in Islamabad with a truck full of explosives, killing at least 54.
— August 21: Suicide bombers blow themselves up at two gates of a weapons factory in the town of Wah, killing at least 67 people.
— December 27: Former Prime Minister Benazir Bhutto and 20 other people are killed in a suicide bombing and shooting attack in Rawalpindi.
— October 18: Suicide bombing aimed at Bhutto kills some 150 people in Karachi during celebrations welcoming her home from self-exile.
— July 3-11: An eight-day standoff between security forces and militants inside the compound of the Red Mosque, or Lal Masjid, kills 102 people.
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