SUSPECTED US UNMANNED aircraft fired six missiles at a vehicle in Pakistan’s tribal region near the Afghan border today, killing six alleged militants, Pakistani intelligence officials said.

The high number of missiles used in the attack in the Datta Khel area of North Waziristan seemed to indicate an important militant was targeted. But the identities of those killed were as yet unknown, said the officials, speaking on condition of anonymity because they were not authorized to talk to the media.

Datta Khel is an important base for militants from the Afghan and Pakistani Taliban and also from al-Qaeda. The US has carried out many strikes in the area in the past, although Washington refuses to acknowledge the CIA-run drone program in Pakistan publicly.

A house was also partly destroyed in Sunday’s attack, said the intelligence officials. It was unclear whether any of the six suspected militants who were killed were in the house at the time, or all in the vehicle.

The US has pushed Pakistan to target militants based in North Waziristan who stage cross-border attacks against American troops in Afghanistan. Washington has particularly focused on the Haqqani network, which it deems the most dangerous threat in Afghanistan.

The Pakistani military has refused, saying its troops are stretched too thin by operations in other parts of the tribal region against the Pakistani branch of Taliban, which poses a direct threat to the state. The Afghan Taliban and their allies, like the Haqqani network, have focused their attacks in Afghanistan and are seen by Islamabad as less of a threat.

Many analysts also believe Pakistan wants to preserve long-standing ties with these groups because they could be important allies in Afghanistan after foreign forces withdraw.

Given Pakistan’s resistance, the US has significantly stepped up the number of drone strikes in North Waziristan and other parts of the tribal region since President Barack Obama took office.