FACTBOX - U.S. drone strikes in Pakistan

ISLAMABAD (Reuters) - A pilotless U.S. drone fired two missiles into a Taliban communication centre in an ethnic Pashtun tribal region on the Afghan border, killing five militants, intelligence officials said on Saturday.

The attack on the centre run by Baitullah Mehsud, Pakistani Taliban chief and an al Qaeda ally, took place late on Friday in the South Waziristan region.

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 48 drone air strikes since the beginning of last year, most since September, killing about 465 people, including many foreign militants, according to a tally of reports from Pakistani intelligence agents, district government officials and residents.