Q+A: What is behind U.S. drone attacks in Pakistan?

(Reuters) - A U.S. drone fired two missiles on Thursday at a compound in northwest Pakistan where Pakistani Taliban chief Hakimullah Mehsud was believed to have been, but it was not clear if he was among 12 militants killed, Pakistani officials said.

The U.S. Central Intelligence Agency operates the missile-firing Predator and Reaper drones. Here are some questions and answers about the strikes:

WHY DOES THE UNITED STATES ATTACK?

Many al Qaeda and Taliban members fled to northwestern Pakistan's ungoverned ethnic Pashtun belt after U.S.-led forces ousted Afghanistan's Taliban government in 2001. From sanctuaries there, the militants have orchestrated insurgencies in Afghanistan and Pakistan. The United States and Afghanistan have pressed Pakistan to eliminate the sanctuaries. Apparently frustrated by Pakistan's inability to do so, the United States itself is hitting the militants. An option being considered as the United States struggles to bring stability to Afghanistan is for more missile attacks in Pakistan, and perhaps expanding the strikes to the southwestern province of Baluchistan.

HOW MANY ATTACKS AND WHERE?

There have been eight strikes in northwest Pakistan since the December 30 bomb attack on the CIA, all in or on the border of North Waziristan where Afghan Taliban factions, including one run by veteran Islamist commander Jalaluddin Haqqani, have strongholds. The United States carried out 51 drone air strikes in Pakistan last year, killing about 460 people, including many foreign militants, according to a tally of reports from Pakistani officials and residents. In 2008, there were 32 strikes, most in the last four months of that year, that killed about 240 people.

WHERE ARE THE DRONES LAUNCHED FROM?

A senior U.S. lawmaker, Senator Dianne Feinstein, told a U.S. Senate hearing in February last year that the drones were being flown from an air base inside Pakistan. Pakistan denied that, saying it had never granted permission for the strikes.

WHAT IS PAKISTAN'S POSITION?

Pakistan officially objects to the U.S. drone strikes as a violation of its sovereignty, and Foreign Minister Shah Mehmood Qureshi said Wednesday the attacks could endanger ties between the two allies.

While Pakistan is believed to have quietly approved strikes on militants attacking in Pakistan, such as Pakistani Taliban chief Baitullah Mehsud, killed by a drone last August, it worries the strikes undermine efforts to deal with militancy because civilian casualties inflame public anger and bolster support for the fighters. Pakistan has pressed the United States to provide it with drones to allow it to conduct its own attacks.

WHAT IS THE U.S. POSITION?

U.S. officials say the missile strikes are carried out under an agreement with Islamabad that allows Pakistani leaders to decry the attacks in public. U.S. sources said in May that Washington had given Pakistan data on militants from surveillance drones in Pakistani airspace under an agreement with Islamabad.

WHO HAS BEEN KILLED?

The following prominent militants have been reported killed over the past couple of years but not all of the deaths have been confirmed. In the past, some militants reported killed in drone strikes have turned up alive.

January 28, 2008 - A senior al Qaeda member, Abu Laith al-Libi. July 28 - An al Qaeda chemical and biological weapons expert, Abu Khabab al-Masri.

November 22 - Rashid Rauf, a Briton with al Qaeda links and the suspected ringleader of a 2006 plot to blow up airliners over the Atlantic, was reported killed though doubts have since arisen. An Egyptian named as Abu Zubair al-Masri was also reported killed. January 1, 2009 - Pakistani agents said a drone killed three foreign fighters. A week later, a U.S. counter-terrorism official said al Qaeda's operational chief, Usama al-Kini, and an aide had been killed.

August 5 - Pakistani Taliban chief Baitullah Mehsud was killed in a South Waziristan stronghold.

August 27 - An al Qaeda-linked Uzbek militant leader, Tahir Yuldashev, was killed in South Waziristan, Pakistani intelligence agency officials said.

September 14 - Senior Uzbek militant Najmiddin Kamolitdinovic Jalolov was killed in North Waziristan.

December 11 - A U.S. counter-terrorism official said Saleh al-Somali, a senior al-Qaeda operations planner, was believed to have been killed in a recent strike.

(Compiled by Islamabad Newsroom; Editing by Alex Richardson)