A U.S. drone strike has killed three suspected militants in northwestern Pakistan near the Afghan border.

Pakistani intelligence officials say the drone fired two missiles Thursday into a house in Mubarak Shahi, located in the North Waziristan tribal area.

North Waziristan is a stronghold of al-Qaida- and Taliban-linked militants.

Pakistan has repeatedly criticized U.S. drone attacks as a violation of the country's sovereignty, but American officials say the strikes are a key tool in defeating militants.