A. The Pakistani Taliban Movement, or Tehrik-i-Taliban Pakistan, is an umbrella organization loosely uniting up to 30 groups of Pakistani militants along the tribal areas bordering Afghanistan. Its headquarters, though, is in North and South Waziristan, the jihadist hub at the western end of the tribal belt, where it was formally founded in 2007 by a prominent Pashtun commander, Baitullah Meshud.
Many Pakistani Taliban commanders had fought in Afghanistan as part of the movement that swept to power in Kabul. When American forces ousted that movement in 2001, many of its leaders fled across the border into Pakistan. The Pakistanis among them played host to their Afghan counterparts — as well as hundreds of fighters from Al Qaeda — providing them with shelter, logistical support and recruits.
The Afghan Taliban and Qaeda fighters steadily radicalized the tribal regions, encouraging the Pakistani Taliban to spread their influence across the mountainous region and beyond into Pakistan’s settled areas and main cities.
The militant groups resisted the Pakistani military’s efforts to impose control. They sometimes cooperated in cease-fire agreements with the Pakistani military and then reneged months later. After Mr. Mehsud created Tehrik-i-Taliban, he led the group in attacks against the Pakistani state, striking military and civilian targets in various cities. The group accused the Pakistani government of siding with the United States in its war against terror, and vowed revenge for the killing of Pakistani civilians in the 2006 bombing of a madrasa in North-West Frontier Province, which was renamed Khyber-Pakhtunkhwa in 2010, and in the Red Mosque siege in Islamabad in 2007.
The United States designated the Pakistani Taliban a terrorist organization in September 2010 and placed a $5 million reward for information leading to the arrest of their leader, Hakimullah Mehsud.
Q. Who is Hakimullah Mehsud, and what does his death mean for the Pakistani Taliban?
On Oct. 9, Hakimullah Mehsud appeared in a BBC report, saying he was ready to enter negotiations with the Pakistani government.
A. Mr. Mehsud became the leader of the Pakistani Taliban after an American drone strike killed Baitullah Mehsud in August 2009. A onetime driver for the Taliban who had risen to prominence through a series of daring attacks, he played a major role in the humiliating kidnapping of 250 Pakistani soldiers in 2007. He later stole American jeeps as they were being transported to Afghanistan and was filmed driving around in one.
Mr. Mehsud proved a wayward, vicious leader. He appeared at the execution of a former Pakistani intelligence officer, Sultan Amir, known as Colonel Imam, in 2011. Colonel Imam had long been a trainer and mentor to the Taliban in Afghanistan and Pakistan, yet Mr. Mehsud ignored efforts to intercede on his behalf by senior Taliban figures, including Mullah Mohammad Omar, the Afghan Taliban leader, and Sirajuddin Haqqani, the leader of the powerful Haqqani network.
Hunted by American drones, Mr. Mehsud adopted a low profile in recent months and was rarely seen in the news media. But in a BBC interview that was broadcast in October, he vowed to continue his campaign of violence. He was aware that the C.I.A. was seeking to kill him, he said, adding: “Don’t be afraid. We all have to die someday.”
Mr. Mehsud’s deputy, Abdullah Behar, was among the four people who were killed with him, according to a Pakistani official, and it was not clear who might succeed him. Mr. Behar had just assumed the deputy post from Latif Mehsud, a militant commander whom American forces in Afghanistan detained last month.
Q. What are the most significant attacks claimed by the Pakistani Taliban?
A. Under Baitullah Mehsud, the Pakistani Taliban and affiliated militant groups unleashed a series of devastating bomb blasts in Pakistan’s cities. They attacked Pakistani military and intelligence targets, including a suicide bombing in the canteen of Pakistan’s elite special forces commandos, the Special Services Groups, and a hostage-taking inside the army’s General Staff Headquarters in Rawalpindi. The Pakistani Taliban were also behind fatal bomb blasts on softer targets like the Marriott Hotel in Islamabad in September 2008 and the Pearl Continental Hotel in Peshawar in 2009.
Under Hakimullah Mehsud, the group demonstrated a close alliance with Al Qaeda. He claimed a role in the suicide bombing by a Jordanian double agent that killed seven C.I.A. officials and a Jordanian intelligence official at Camp Chapman in eastern Afghanistan in December 2009, mounted in revenge for the killing of Beitullah Mehsud.
The bomber, Humam Khalil Abu Mulal al-Balawi, had been recruited by Jordanian intelligence and was being used to try to undermine Al Qaeda’s leadership based in Pakistan’s tribal areas. The Taliban disseminated video footage showing Mr. Mehsud beside the Jordanian before the bomber traveled from North Waziristan to Afghanistan to carry out the attack.
Mehsud later trained Faisal Shahzad, a Pakistani-American who tried to set off a car bomb in Times Square in New York City in 2010.
In 2012, the Pakistani Taliban shot Malala Yousafzai, a Pakistani schoolgirl in the Swat Valley, in the head for advocating the education of girls. Ms. Yousafzai went on to become a worldwide symbol of the group’s indiscriminate violence and subjugation of women and girls, traveling to New York to give a speech at the United Nations. She and her family have moved to England, in part because the Pakistani Taliban have vowed to attack her again.
Q. What relationship do the Pakistani Taliban have now to the Afghan Taliban?
A. The group owes allegiance to the Afghan Taliban leader, Mullah Mohammed Omar, and cooperates closely with the Afghan movement in its insurgency in Afghanistan, providing men, logistics and rear bases for the Afghan Taliban. It has trained and dispatched hundreds of suicide bombers from Pakistan’s tribal areas into Afghanistan. The movement shares a close relationship with the Haqqani network, the most hard-core section of the Afghan Taliban operating out of North Waziristan, which has been behind repeated suicide attacks in and around Kabul and eastern Afghanistan. The Pakistani Taliban are generally seen to follow the lead of the Haqqani network’s boss, Sirajuddin Haqqani. The two also cooperate and provide safe haven for Qaeda operatives, including Al Qaeda’s leader, Ayman al-Zawahiri. Pakistani intelligence, which has longstanding ties with the Haqqani network, has sought to turn the Pakistani Taliban to fight Western forces in Afghanistan and desist from attacks against Pakistan.