The United States has provided “very limited support” to the Taliban in its fight against ISIS in the eastern Afghanistan province of Nangarhar, U.S. Central Commander head Gen. Frank McKenzie told lawmakers Tuesday.

McKenzie provided almost no details about the support, a startling revelation that comes as critics of the peace deal with the Taliban warn against trusting the group’s counterterrorism promises.

According to a defense official who spoke to Defense One later in the day, American forces “essentially stopped engaging, in general, Taliban units actively engaged in fighting with ISIS-K,” the ISIS branch in Afghanistan. The U.S. also carried out strikes on known ISIS-K locations, that official said, but emphasized that those strikes were not coordinated with the Taliban.

In testimony before the House Armed Services Committee on Tuesday, McKenzie was pressed by skeptical lawmakers on whether the Taliban has the military capability to act as a counterterrorism force against ISIS or al Qaeda in the war-torn country, should the U.S. leave.

"Over the last several months in eastern Afghanistan, we've watched the Taliban compress and crush ISIS presence on the ground in southern Nangarhar province — and they've been very effective doing that,” McKenzie said. “It was a bloody mess, but they did it. In fact, ISIS really now no longer holds ground in Nangarhar province.”

Then, asked directly if the Taliban had any U.S. assistance, he answered: “There was very limited support from us – and I would characterize that as very limited support.”

Defense Department officials, speaking later in the day to reporters at the Pentagon, declined to provide any details.

"I don't have any specifics to provide you, but that's the hope, in that: every force there is countering ISIS. Every force there is countering al Qaeda,” said Rear Adm. William Byrne, vice director on the Joint Chiefs of Staff.

On Capitol Hill, Democrats and hawkish Republicans have been raising alarm bells about the newly minted agreement between the Taliban and Washington, saying it places too much faith in the group’s will and capability to act as a legitimate counterterrorism partner. The agreement stipulates that the Taliban will guarantee Afghanistan will not be used by al Qaeda or other terror groups to attack the United States. That is a lower bar than the U.S. had sought earlier: that the Taliban explicitly renounce al Qaeda, which carried out the Sept. 11 attacks.

Before the deal was signed on Feb. 29, 22 Republicans led by Rep. Liz Cheney, R-Wyo., the daughter of the former vice president, warned that the Taliban “has a history of extracting concessions in exchange for false assurances” and asked for assurances that Trump administration would not be “pretending that the Taliban is a reliable counter-terrorism partner.”

Yet Trump himself has appeared enthusiastic about the idea that the Taliban might help take up the counterterrorism mission against ISIS and al Qaeda that remains one of the reasons officials cite for remaining in Afghanistan.

“They will be killing terrorists, killing some very bad people,” Trump said in a White House news conference the day the accord was signed. “We very much hope they will be doing what they said.”

McKenzie’s remarks on Tuesday caught former Pentagon officials by surprise. Jason Campbell, who was Trump’s top Afghanistan policy official at the Defense Department until late 2018, said that he was unaware of any support provided to Taliban at least until his departure.

“‘Limited support’ could be as basic as, ‘we’ve agreed not to target Taliban formations in this part of the country as long as they are willing to continue their offensive movements against ISIS elements’,” he said. (The Taliban and ISIS have been clashing in several provinces for several years.) “It could be just a sort of a nonaggression pact on the part of the U.S. and the Taliban [in that region].”

“That wouldn’t necessarily float up to the policy level in the Pentagon if it were decided by a more localized battalion or brigade or the [Resolute Support] commander,” he said. “That certainly could have happened without it being the subject of a deputies committee meeting.”

But he said that if it’s anything more significant than what the defense official described to Defense One — including passing any intelligence information on ISIS locations through informal channels, for example — ”I think anything beyond that beyond that would likely have to be looked at closely to classify it as ‘very limited.’”

For one thing, Campbell noted, the rules about sharing intelligence with any non-U.S. forces are extremely tight — ”nevermind an organization like the Taliban.”

McKenzie gave a dark assessment of the implementation of the deal so far, telling lawmakers that he would recommend against a complete withdrawal of U.S. troops from Afghanistan, as envisioned by the deal, if Taliban attacks on Afghan forces continue at the pace that they have signed the Feb. 29 signing. The first wave of the drawdown, from roughly 13,000 to 8,600, began yesterday. McKenzie said military planning for the complete withdrawal — expected in 14 months if the Taliban abides by its counterterrorism commitments — has yet to begin.

“To date, Taliban attacks are higher than we believe are consistent with an idea to actually carry out this plan,” he said.

While it’s clear that the Taliban is actively fighting ISIS, he said, he is far less sanguine that they will sever ties with al Qaeda.

“It is more a question of will than capability, and that will have to be developed in the fullness of time,” McKenzie said of the Taliban’s counterterrorism capabilities. “It's less a question of will against ISIS than it is against al Qaeda."

“I defer to no one in my distrust of the Taliban,” McKenzie said.