The Pentagon will not pay Pakistan $300 million in military reimbursements after U.S. Secretary of Defense Ash Carter decided not to tell Congress that Pakistan was taking adequate action against the Haqqani network, an official said.

Relations between the two countries have been frayed over the past decade, with U.S. officials frustrated by what they term Islamabad’s unwillingness to act against Islamist groups such as the Afghan Taliban and the Haqqani network. “The funds could not be released to the Government of Pakistan at this time because the Secretary has not yet certified that Pakistan has taken sufficient action against the Haqqani network,” Pentagon spokesman Adam Stump said on Wednesday.

The $300 million comes under the Coalition Support Fund (CSF), a U.S. Defense Department programme to reimburse allies that have incurred costs in supporting counter-terrorist operations. Pakistan is the largest recipient. According to Pentagon data, about $14 billion has already been paid to Pakistan since 2002.

“Pakistan does not draw any distinction between any terrorists and we have taken up the fight against terrorism,” Foreign Office spokesman Nafees Zakaria told reporters in Islamabad on Thursday.