In retaliation for the last week's attack on Jinnah airport in Karachi, Pakistan, U.S. drones fired missiles at Taliban encampments in the country, killing at least 13 militants.

It was the first strike by a CIA drone in Pakistan in nearly six months. Government officials told Reuters that Islamabad gave its "express approval" for the attacks, but the country's Ministry of Foreign Affairs issued a statement in response to the strikes, calling them violation of its sovereignty. The Pakistani government has been vocally against U.S. drone strikes in the past.

One drone fired missiles on a Taliban hideout late yesterday, killing three according to the AP and six according to Reuters, and another killed at least 10 in a separate compound early this morning. Both strikes occurred in Pakistan's North Waziristan region.

The identities of those who were killed have not been published, but intelligence officials said they were likely to be affiliated with the Haqqani network, which has a strong presence in the area.

A government official told Reuters that behind closed doors, Pakistan is becoming more accepting of drone strikes, despite its official stance:

"The attacks were launched with the express approval of the Pakistan government and army," said a top government official, requesting not to be named as he was not authorised to discuss the issue with the media.

"It is now policy that the Americans will not use drones without permission from the security establishment here. There will be complete coordination and Pakistan will be in the loop.

"We understand that drones will be an important part of our fight against the Taliban now," the official added.

Earlier this week, the Taliban promised "full-out war with the Pakistani state."

[Image via AP]