The US commander of Nato troops in Afghanistan on Friday accused the Pakistan-based Haqqani network of orchestrating a 12-hour siege on a lakeside hotel in Kabul that killed 18 people.
General John Allen blamed the al Qaeda-linked network in a statement just weeks after US defense secretary Leon Panetta said the United States was running out of patience with Pakistan over its refusal to eliminate terror havens.
The Haqqani group, believed to be based in Pakistan's lawless tribal district of North Waziristan, is blamed for some of the deadliest attacks in Afghanistan's 10-year war.
"Afghan national security forces and coalition military sources acknowledge that this attack bears the signature of the Haqqani network, which continues to target and kill innocent Afghans and blatantly violate Afghan sovereignty from the safety of Pakistan," Allen said.
Nato's International Security Assistance Force confirmed that its troops and Afghan security forces had responded to the assault.
But Allen emphasised the role played by Afghan forces, seeking to downplay concerns about the ability of the local police and army to manage after Nato combat troops withdraw in 2014.
Allen said he had been "extremely impressed" with the Afghan response.
"There should be little doubt about their ability and capability to protect the Afghan people in the years ahead," he said.
He condemned the "unspeakably brutal attack" on civilians and paid tribute to the security guards and law enforcement officers who died in order to protect women and children.
In Afghanistan on June 7, Panetta warned Pakistan that Washington was losing patience over its failure to eliminate safe havens for the Haqqanis and other Islamist militants who attack US troops across the border.