FACTBOX: U.S. drone strikes in Pakistan

ISLAMABAD (Reuters) - Suspected U.S. drones fired six missiles into a Pakistani Taliban training camp near the Afghan border on Wednesday, killing six militants, government and intelligence agency officials said.

The pre-dawn attack was in the South Waziristan region, in a stronghold of Pakistani Taliban leader Baitullah Mehsud, they said.

Here are some facts about the U.S. missile attacks, the controversy they have caused, and a list of some of the more prominent militants killed, according to Pakistani officials.

WHY DOES THE UNITED STATES ATTACK?

Many al Qaeda members and Taliban fled to northwestern Pakistan's ungoverned ethnic Pashtun belt after U.S.-led soldiers ousted Afghanistan's Taliban government in 2001. From their 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 is hitting the militants itself.

HOW MANY ATTACKS?

The United States has carried out about 46 drone air strikes since the beginning of last year, most since September, killing about 430 people, including many foreign militants, according to a tally of reports from Pakistani intelligence agents, district government officials and residents.

SOME OF THE PEOPLE REPORTED KILLED

January 28, 2008 - A senior al Qaeda member, Abu Laith al-Libi, was killed in a strike in North Waziristan.