US Defence Secretary Leon Panetta has backed the use of drones to target militants in Pakistan, two days after a missile strike reportedly killed al-Qaeda leader Abu Yahya al-Libi.
Mr Panetta said the US had made it “very clear that we are going to continue to defend ourselves”.
He made the comments while attending a conference in neighbouring India.
On Tuesday, Pakistan summoned the US charge d’affaires to reiterate its “serious concerns” about drone strikes.
There have been eight US drone strikes in the past two weeks despite Islamabad’s demands for them to be stopped.
Pakistan says the drone attacks fuel anti-US sentiment and claim civilian casualties along with militants. The US insists the strikes are effective.
‘Our sovereignty’
US officials say Abu Yahya al-Libi died when two missiles struck a suspected militant compound early on Monday in Hesokhel, a village to the east of Miranshah, the main town of the North Waziristan tribal area.
At least 14 people are thought to have been killed alongside him.
The White House said Libi’s death dealt a heavy blow to al-Qaeda as he played a critical role in its planning of operations against the West.
“There is no-one who even comes close in terms of replacing the expertise al-Qaeda has just lost,” one official said.
Speaking in Delhi on Wednesday, Mr Panetta made it clear that the US would continue to use unmanned drone aircraft to kill militants in Pakistan, dismissing complaints that its sovereignty had been violated.
“We have made it very clear that we are going to continue to defend ourselves,” he said. “This is about our sovereignty as well.”