After attacks in Kabul killed more than 50 people this month, Afghan President Ashraf Ghani accused Pakistan of being complicit in the violence by sheltering Afghan Taliban leaders. (Massoud Hossaini/AP)

The Pentagon could withhold hundreds of millions of dollars from Pakistan’s military over concerns that it is not doing enough to combat insurgent groups that plan and coordinate attacks from its soil on neighboring Afghanistan, according to U.S. and Pakistani officials.

Since 2002, the Pentagon has reimbursed Pakistan about $13 billion for its support of the U.S.-led war in Afghanistan. But Congress made part of this year’s $1.1 billion payment contingent on Pakistan’s willingness to crack down on the Haqqani network, a Pakistan-based group affiliated with the Taliban, that is responsible for some of the bloodiest attacks of the Afghan war.

Although officials say that most of the 2015 payment is moving through the pipeline, the Pentagon recently informed Pakistan that a final $300 million may be withheld if the U.S. defense secretary cannot certify sufficient action against the Haqqanis.

The move could send U.S.-Pakistan relations, which have greatly improved in the past year, into another period of tension.

The possible payment delay, first reported by Pakistan’s Dawn newspaper, comes as Afghan President Ashraf Ghani and other Afghan officials are urging the United States to get tougher on Pakistan over alleged ties between Pakistani intelligence agencies and the Haqqani network, amid a new series of attacks in Kabul, the Afghan capital.

A Pakistani Foreign Ministry official, who was not authorized to talk to the news media, said the full payment is “important to us both politically and financially,” as Pakistan continues a major offensive begun last year against militants in its western tribal regions.

At a news briefing in Islamabad on Thursday, Foreign Ministry spokesman Qazi Khalilullah declined to comment, saying only that Pakistani and U.S. officials are “engaged in consultations on various issues,” including the future of the Coalition Support Fund.

“Pakistan and the U.S. enjoy good relations, which are on an upward trajectory,” he said.

A senior Obama administration official praised the Pakistani military offensive, saying it has “significantly disrupted a number of terrorist organizations.” More than 1,000 Pakistani troops have been lost in the fight, said the official, who spoke on the condition of anonymity about bilateral U.S. talks with Pakistan.

“But what we’ve said to them is that at the end of the day, the overall success of the operation will be whether the militants are truly removed,” the official said. “Some of them” have gone back to Afghanistan, but “some have not.”

“The problem is that the Haqqanis,” who the Americans agree have been largely driven out of their longtime headquarters in the town of Miran Shah in the North Waziristan tribal area, “have been able to reconstitute in a meaningful way elsewhere in Pakistan, and are currently involved in lethal attack planning against high-profile targets, including in Kabul,” the official said.

“That is dangerous to U.S. forces, disruptive to progress between Afghanistan and Pakistan . . . and goes against commitments that the Pakistani government has made,” he said.

Relations between Pakistan and Afghanistan also had improved noticeably, and Pakistan sponsored peace talks between the Afghan government and the Taliban leadership early this summer. But the relationship soured in late July when news broke that Taliban supreme leader Mohammad Omar had died two years earlier, possibly on Pakistani soil. Pakistan had always denied that Omar was in the country.

The Taliban’s senior council then met in the Pakistani city of Quetta and appointed a new ­supreme leader, Akhtar Mohammad Mansour. Sirajuddin Haqqani, an influential member of the Haqqani family, became the second in command.

Other Taliban leaders have rejected the appointments, saying Pakistani intelligence officials had too much influence over the process. After attacks in Kabul killed more than 50 people this month, Ghani accused Pakistan of being complicit in the violence by sheltering Afghan Taliban leaders.

“If Pakistan cannot bring the Taliban to the negotiating table, at least they can shut down their centers and not take their wounded to hospitals,” Ghani said.

Many Afghan leaders and commentators are even more critical of Pakistan, and they say the United States should be doing more to pressure the country into severing its relationship with the Taliban.

Aimal Faizi, who served as press secretary for Hamid Karzai, Ghani’s predecessor, wrote an op-ed for the Al Jazeera network this week accusing the U.S. government of glossing “over Pakistan’s support for state-sponsored terrorism.”

On Wednesday, Aizaz Ahmad Chaudhry, a senior Pakistani Foreign Ministry official, summoned Afghan Ambassador Janan Mosazai to condemn what he called an Afghan media campaign to “malign” Pakistan.

U.S. payments through the Coalition Support Fund — reimbursement for expenses incurred in support of U.S. antiterrorism goals and operations in Afghanistan — account for about half of all U.S. aid to Pakistan since 2002, according to the Congressional Research Service.

The senior Obama administration official said $100 million of this year’s $1.1 billion CSF appropriation has been paid, and “an additional $300 million is already in the pipeline.”

“There’s an additional $400 million that they can get without certification,” the official said. The holdup of the final $300 million, he said, “is not something that is going to happen soon. It’s just something that [the Defense Department] has reminded the Pakistanis of.”

DeYoung reported from Washington. Shaiq Hussain in Islamabad contributed to this report.

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