WASHINGTON — The Biden administration warned the Kremlin on Thursday over the C.I.A.’s conclusion that Russia had covertly offered payments to militants to encourage more killings of American and coalition troops in Afghanistan, delivering the diplomatic admonition as it imposed sanctions on Moscow over its hacking and election interference.
But the administration stopped short of inflicting sanctions on any Russian officials over the suspected bounties, making clear that the available evidence about what happened — primarily what Afghan detainees told interrogators — continues to fall short of definitively proving the C.I.A.’s assessment that Russia likely paid money to reward attacks.
The intelligence community, a senior administration official told reporters, “assesses with low to moderate confidence that Russian intelligence officers sought to encourage Taliban attacks against U.S. and coalition personnel in Afghanistan in 2019, and perhaps earlier, including through financial incentives and compensation.”
The New York Times first reported last summer the existence of the C.I.A.’s assessment and that the National Security Council had led an interagency process to develop a range of response options — but that months had passed and the Trump White House had failed to authorize any response, not even a diplomatic protest.
The Times also reported that the available evidence behind that assessment centered on what detainees who were believed to be part of a criminal-militant network linked to the Taliban had told interrogators, along with suspicious travel patterns and financial transfers, and that the C.I.A. placed medium confidence in its conclusion.
But, it also reported, the National Security Agency — which is focused on electronic surveillance — placed lower confidence in the assessment, citing the lack of smoking-gun electronic intercepts. Analysts at two other agencies that were consulted, the National Counterterrorism Center and the Defense Intelligence Agency, were also said to split, with the former backing the C.I.A. and the latter the National Security Agency.
Former intelligence officials, including in testimony about the issue before Congress, have noted that it is rare in the murky world of intelligence to have courtroom levels of proof beyond a reasonable doubt about what an adversary is covertly doing.
The re-scrub of available evidence by President Biden’s administration had not uncovered anything new and significant enough to bring greater clarity to that muddied intelligence portrait, so the disagreement over confidence levels remained, an official familiar with internal deliberations said.
The Biden official’s explanation to reporters dovetailed with that account.
Intelligence agencies, the official explained, “have low to moderate confidence in this judgment in part because it relies on detainee reporting, and due to the challenging operating environment, in Afghanistan.”
“Our conclusion,” the official continued, “is based on information and evidence of connections between criminal agents in Afghanistan and elements of the Russian government.”
The official did not explain further. But one problem with the available evidence, The Times also reported last year, was that the leader of the suspected criminal-militant network who was believed to have interacted directly with Russian intelligence officials, Rahmatullah Azizi, had fled to Russia — possibly while using a passport linked to a Russian spy agency.
As a result, the detainees who recounted to interrogators what they were told about the purported arrangement were not themselves in the room for conversations with Russian intelligence officials. Without an electronic intercept, either, there was a pattern of evidence that fit the C.I.A.’s assessment but no explicit eyewitness account of the interactions.
The Russian government has denied that it covertly offered or paid bounties to drive up attacks on American and coalition troops in Afghanistan.
The public disclosure of the C.I.A.’s assessment — and the White House’s months of inaction in response — prompted a bipartisan uproar in Congress. Defending the inaction, President Donald J. Trump labeled the reporting “a hoax” and his White House denied that he had been told about it, seeking to dismiss the intelligence assessment as too weak to be taken seriously.
In fact, it had been included in his written intelligence briefing in late February 2020 and disseminated more broadly to the intelligence community in early May.
But it was also true that analysts at the National Security Agency disagreed with the C.I.A. over how much confidence to place in the agency’s conclusion, based on the imperfect array of available evidence. The Trump administration played up that split.
In testimony before Congress about the issue, Michael J. Morell, a former acting C.I.A. director, disputed the White House’s suggestion that such an assessment had to be unanimously backed by intelligence agencies to be taken seriously.
In previous administrations, he said last July, if the intelligence community assessed such information at any level of confidence, officials would have told both the president and congressional leaders immediately about that judgment and any dissent. If the confidence level were low, he said, an administration would seek more information before acting, while a medium- or high-confidence assessment would most likely result in a response.
“You never have certainty in intelligence,” Mr. Morell added.
Mr. Trump never raised the issue of the bounty intelligence in his conversations with President Vladimir V. Putin of Russia. But after the C.I.A.’s assessment became public, senior military and diplomatic officials, including the secretary of state at the time, Mike Pompeo, warned their counterparts after all.
“If the Russians are offering money to kill Americans or, for that matter, other Westerners as well, there will be an enormous price to pay. That’s what I shared with Foreign Minister Lavrov,” Mr. Pompeo said in August during a trip to the Czech Republic. “I know our military has talked to their senior leaders, as well. We won’t brook that. We won’t tolerate that.”
Still, in testimony before Congress and in other remarks, senior Pentagon officials — caught between not wanting to aggravate the White House and not wanting to appear indifferent about the safety of troops — said they would be outraged if the C.I.A. assessment was correct, but also had yet to see definitive proof.
“It is not closed because we never close investigations that involve threats or potential threats against U.S. forces,” Gen. Kenneth F. McKenzie Jr., the head of the Pentagon’s Central Command, said late last year when asked about the status of the inquiry. “We’re looking at it very hard.”
Meanwhile, as a presidential candidate, Mr. Biden attacked Mr. Trump for failing to do anything about the C.I.A. assessment, portraying it as part of a strange pattern of deference he said Mr. Trump had shown toward Russia. Mr. Biden mentioned the matter in his speech accepting the Democratic nomination and brought it up in his first call as president with Mr. Putin.
While the sanctions imposed on Thursday were based on alleged Russian misdeeds other than the suspected bounties, the senior administration official said the diplomatic action about the available information related to suspected bounties “puts a burden on the Russian government to explain its actions, and take steps to address this disturbing pattern of behavior.”
The official added, “We cannot and will not accept the targeting of our personnel like this.”
Julian E. Barnes and Eric Schmitt contributed reporting.