Pakistan on Thursday condemned the first US drone strikes on its soil this year despite suspicions the two countries coordinated over the attack in the aftermath of a Taliban siege of Karachi airport.
The strikes took place over Wednesday night and early Thursday morning, killing at least 16 militants in the North Waziristan tribal district that lies on the Afghan border, in the first such attacks since December.
They came in the same week as the Taliban claimed responsibility for an all-night siege of Karachi airport that left 37 dead including 10 attackers, shredding a nascent peace process and placing pressure on Islamabad to react decisively.
The foreign office issued a tersely worded statement condemning the strikes as "a violation of Pakistan's sovereignty and territorial integrity".
"Additionally, these strikes have a negative impact on the government's efforts to bring peace and stability in Pakistan and the region," the statement said.
A foreign office spokeswoman told AFP that rumours of Pakistan requesting the attack were "speculation".
But a senior retired diplomat who is familiar with tribal affairs told AFP: "The government must have consented to this attack. It could not have happened without that."
Washington reportedly suspended its drone programme in December to give Islamabad time to pursue a dialogue process with the TTP aimed at ending a seven year insurgency that has claimed thousands of lives.
The dialogue resulted in a month-long ceasefire between March and April but later broke down, with Pakistan resuming air strikes in suspected militant hideouts in the tribal areas.
The army was widely seen as being opposed to the dialogue because of the heavy casualties it has sustained at the hands of the Tehreek-e-Taliban (TTP), which views them as a mercenary force serving foreign interests.
But following the breakdown of the talks and the Karachi attack, observers believe both civil and military authorities are converging on the need for more concerted action.
Leaked documents have shown deep cooperation over drone attacks in the past, but they remain controversial with critics charging they cause many civilian casualties.
Some 2,171 people have been killed in drone attacks since August 2008, according to an AFP tally.
The US drone strikes took place within hours of each other as militants gathered to dig out the bodies and search for the injured.
The first struck a vehicle and a compound in the village of Dargah Mandi in North Waziristan, where almost 60,000 residents have fled since May fearing a long-rumoured offensive.
An intelligence official in Miranshah, the region's main town some 10 kilometres (six miles) east of the village, said the missiles had struck a pick-up truck carrying about six militants and laden with explosives.
"Four of them were Uzbeks and two were Punjabi Taliban," he said, referring to militants from Pakistan's central Punjab province.
The TTP confirmed to AFP on Wednesday that the Karachi airport siege was carried out by Uzbek fighters belonging to the International Movement for Uzbekistan in a "joint operation".
The second strike came early Thursday at the same site as militants gathered to dig-out the bodies of their fallen comrades at the site of the earlier attack, a local security official said..
Prior to the latest strikes, the last drone attack on Pakistani soil occurred on December 25, 2013, killing three suspected militants.