A U.S. drone targeted a residential compound and a vehicle in northwest Pakistan’s restive tribal region close to the Afghan border, killing at least 18 suspected militants, officials said on Wednesday.

The CIA-operated unmanned plane fired four missiles targeting the compound and the vehicle in Danday Darpakhel area in North Waziristan tribal region’s Miranshah on Tuesday night.

“So far the reports show that around 18 people have been killed in the incident,” a security official.

The identity of those killed was immediately not known but the militants linked with al-Qaeda are active in the area.

This was the second drone attack in two months.

Last month, seven militants were killed and three injured when a drone strike targeted a compound in Mangroti village, in the Shawal tehsil of North Waziristan.

Pakistan opposes the drone attacks, saying civilians are killed in the strikes, but U.S. maintains it target militants.

The fresh strike may create tension between the U.S. and the government of Prime Minister Nawaz Sharif, who promised in his election campaign to stop the unilateral drone attacks.