The strikes occurred three minutes apart and took place in the Datta Khel area of the North Waziristan tribal region — the main sanctuary for al-Qaida and Taliban fighters along the Afghan border, said the officials, speaking on condition of anonymity because they were not authorized to talk to the media.

There were conflicting reports about exactly how many suspected militants were killed. One set of Pakistani intelligence officials said 25 people died in the strikes, while another put the number at 34.

The United States began firing missiles at militant targets in Pakistan in 2004, but the pace of the attacks picked up dramatically in 2008. Last year, there were around 120 strikes, which are believed to be carried out by unmanned drone aircraft launched either from Afghanistan or from inside Pakistan. There have been around 20 so far this year.