The US has suspended hundreds of millions of dollars in military aid for Pakistan amidst strained ties with the nation.
White House chief of staff Bill Daley said, "Until we get through these difficulties, we will hold back some of the money that the American taxpayers have committed to give them."
About $800m in military aid and equipment, or over one-third of the more than $2bn in annual US security assistance to Pakistan, could be affected by the suspension.
The aid includes $300m for costs of deploying more than 100,000 soldiers along the Afghan border, as well as hundreds of millions of dollars in training assistance and military hardware.
Equipment such as night vision goggles and helicopter spare parts cannot be set up, certified or used for training because Pakistan has denied visas to the US personnel needed to operate it.
The deliveries were withdrawn after Islamabad ordered more than 100 US Army special forces trainers to leave the country in recent weeks.
US has been spending billions of dollars since 9/11 to help the Pakistan military tackle al-Qaeda and Taliban groups along the border with Afghanistan.