A drone strike on a compound in Pakistan's North Waziristan tribal region has killed at least four suspected militants.
A senior Pakistani security official, speaking under condition of anonymity, said a U.S. drone fired two missiles at a compound in Shahi Khel.
It was unclear who the target of the strike was. Security officials said it was possible more than four people were killed in the attack.
North Waziristan and the other six semiautonomous tribal regions have become havens for Al-Qaeda and Taliban militants.
The Pakistani military launched an offensive in North Waziristan last June and claims more than 1,800 militants have been killed since then.
The Pakistani military has intensified the campaign in North Waziristan in the wake of the December 16 attack on a school in Peshawar that killed 150 people, most of them children.
The Pakistani Taliban claimed responsibility for that attack.