(CNN) -- A suspected U.S. drone strike killed nine militants in Pakistan's tribal region on Sunday, the second such attack in 24 hours in the region, a local government official said.
The drone fired four missiles at a militant compound in Wacha Dana, a village in South Waziristan near the Afghanistan border, the official, Javed Marwat, told CNN.
South Waziristan is one of the seven tribal provinces. The area is thought to be a safe haven for militant groups fueling the insurgency across the border in Afghanistan.
It was the 20th drone strike in Pakistan this year. U.S. officials rarely discuss the CIA's drone program in Pakistan, though privately they have said the covert strikes are legal and an effective tactic in the fight against extremists.
A day earlier, a suspected strike near the town of Wana in the same province killed two militants after the drone fired two missiles at a motorcycle they were riding, Marwat said.
The Obama administration justified its use of unmanned drones to target suspected terrorists overseas in a rare public statement recently, with John Brennan, the president's top counter-terrorism adviser, saying the strikes are conducted "in full accordance with the law."
The program utilizes unmanned aerial vehicles, often equipped with Hellfire missiles, to target al Qaeda operatives in remote locations overseas -- often on the territory of U.S. allies such as Pakistan and Yemen. Brennan said the United States "respects national sovereignty and international law" and is guided by the laws of war in ordering those attacks.