US President Barack Obama has confirmed that unmanned drones regularly strike suspected militants¹ in Pakistan's tribal² areas.

美国总统奥巴马证实，无人驾驶飞机定期在巴基斯坦部落区袭击激进嫌疑分子。

Mr Obama called the strikes a "targeted focused effort at people who are on a list of active terrorists".

The US does not routinely speak publicly about drone operations.

Mr Obama made his comments during an hour-long video "hangout" on Google's social network, Google+, which was also streamed live on YouTube.

More than 130,000 questions were submitted before the hangout began, and six people were invited to join the president online for the event. They were able to ask questions and seek follow-up answers from Mr Obama.

The event ended a week of social media engagement in the wake of Mr Obama's State of the Union address on 24 January.

Obama administration officials, including Vice-President Joe Biden, held Twitter "office hours" last week.

Covert³ war

Asked about the use of drone strikes, which have increased in intensity⁴ during his presidency⁵, he said "a lot of these strikes have been in the Fata", or Pakistan's Federally Administered Tribal Areas.

The strikes target "al-Qaeda suspects who are up in very tough terrain⁶ along the border between Afghanistan and Pakistan," Mr Obama added.

"For us to be able to get them in another way would involve probably a lot more intrusive⁷ military action than the ones we're already engaging in."

Few details are known about the covert US drone operation, which is run by the CIA and targets al-Qaeda and Taliban militants in the mountainous areas along the Afghan-Pakistan border.

According to the AFP news agency, 64 US missile strikes were reported in the area in 2011, down from 101 in 2010.

They often cause outrage⁸ in Pakistan, where many assert that the strikes cause indiscriminate（任意的） civilian⁹ deaths and injuries.

Anti-American feeling flared¹⁰ in Pakistan in the wake of the US special operations mission that killed Osama Bin¹¹ Laden¹² in 2011.