Pakistan retaliated against a NATO airstrike which killed Pakistani troops on Saturday by shutting down supply routes into Afghanistan and calling for the United States to “vacate” an air base allegedly used to launch drone attacks.
The incident marked an escalation in the already tense relations between the U.S. and Pakistan.
Pakistan said 26 soldiers were killed and more wounded in the NATO raid, calling the attack "unprovoked" and "irresponsible," according to news sources.
The closed supply routes are vital for the support of troops, including U.S. and other allied forces, fighting in Afghanistan.
The Pakistani government also demanded that American forces halt operations from Shamsi air base, Fox News reported. The base, located in a remote western region of the country is believed to have housed American armed drones which have struck targets in Afghanistan and Pakistan.
Diplomatic relations have been strained between the U.S. and Pakistan since the U.S. raid that killed Osama bin Laden within Pakistan's borders in May. The country considered it a violation of sovereignty by the United States.
Although the cause remains unclear for the NATO airstrike incident at a Pakistani checkpoint early on Saturday morning, Pakistan's Prime Minister Yusuf Raza Gilani issued similar criticism.
"This is an attack on Pakistan's sovereignty," Gilani said, according to Reuters. "We will not let any harm come to Pakistan's sovereignty and solidarity."
In October, relations took another hit when retired Admiral Mike Mullen formerly chairman of the Joint Chiefs of Staff told lawmakers that Pakistan’s intelligence agency, ISI, was linked to the Taliban-allied Haqqani network which has been blamed for attacks on American servicemen.
Marine Gen. John R. Allen, the commander of the war in Afghanistan, offered condolences to the families of Pakistani Security Forces killed or injured in the raid.
"This incident has my highest personal attention and my commitment to thoroughly investigate it to determine the facts," Allen told CNN.
The American ambassador to Pakistan Cameron Munter expressed regret for the NATO attack. “I regret the loss of life of any Pakistani servicemen and pledge that the United States will work closely with Pakistan to investigate this incident,” the ambassador said in a statement.
This story was posted at 11:37 a.m. and has been updated.
Meghashyam Mali contributed