WASHINGTON (NYTIMES) - United States intelligence officers and Special Operations forces in Afghanistan alerted their superiors as early as January to a suspected Russian plot to pay bounties to the Taleban to kill US troops in Afghanistan, according to officials briefed on the matter.

They believed at least one US troop death was the result of the bounties, two of the officials said.

The crucial information that led the spies and commandos to focus on the bounties included the recovery of a large amount of American cash from a raid on a Taleban outpost that prompted suspicions.

Interrogations of captured militants and criminals played a central role in making the intelligence community confident in its assessment that the Russians had offered and paid bounties in 2019, another official has said.

Armed with this information, military and intelligence officials have been reviewing US and other coalition combat casualties over the past 18 months to determine whether any were victims of the plot.

Four Americans were killed in combat in early 2020, but the Taleban have not attacked US positions since a February agreement to end the long-running war in Afghanistan.

The details added to the picture of the classified intelligence assessment, which The New York Times reported last Friday (June 26) has been under discussion inside the Trump administration since at least March, and emerged as the White House confronted a growing chorus of criticism on Sunday over its apparent failure to authorise a response to Russia.

President Donald Trump defended himself by denying the Times report that he had been briefed on the intelligence, expanding on a similar White House rebuttal a day earlier. But leading congressional Democrats and some Republicans demanded a response to Russia that, according to officials, the administration has yet to authorise.

The president "needs to immediately expose and handle this, and stop Russia's shadow war", Republican Representative Adam Kinzinger, a member of the House Foreign Affairs Committee, wrote on Twitter.

Appearing on the ABC programme This Week, House Speaker Nancy Pelosi said she had not been briefed on the intelligence assessment and had asked for an immediate report to Congress. She accused Mr Trump of wanting "to ignore" any charges against Russia.

"Russia has never got over the humiliation they suffered in Afghanistan, and now they are taking it out on us, our troops," she said of the Soviet Union's bloody war there in the 1980s. "This is totally outrageous. You would think that the minute the president heard of it, he would want to know more instead of denying that he knew anything."

Spokesmen for the CIA, the Director of National Intelligence and the Pentagon declined to comment on the new findings. A National Security Council spokesman did not immediately respond to a request for comment.

Though White House press secretary Kayleigh McEnany said last Saturday that Mr Trump had not been briefed about the intelligence report, one US official had told The Times that the report was briefed to the highest levels of the White House. Another said it was included in the President's Daily Brief, a compendium of foreign policy and national security intelligence compiled for Mr Trump to read.

Ms McEnany did not challenge The Times' reporting on the existence of the intelligence assessment, a National Security Council interagency meeting about it in late March and the White House's inaction. Multiple other news organisations also subsequently reported on the assessment.

The officials briefed on the matter said the assessment had been treated as a closely held secret but that the administration expanded briefings about it over the last week - including sharing information about it with the British government, whose forces were among those said to have been targeted.

In a statement in response to questions, Senator Mitch McConnell of Kentucky, the Senate majority leader, said he had long warned about Russia's work to undermine American interests in the Middle East and south-west Asia and noted that he wrote an amendment last year rebuking Mr Trump's withdrawal of forces from Syria, where they are facing fighters for Islamic State, and Afghanistan.

"The United States needs to prioritise defence resources, maintain a sufficient regional military presence and continue to impose serious consequences on those who threaten us and our allies - like our strikes in Syria and Afghanistan against ISIS, the Taleban and Russian mercenary forces that threatened our partners," Mr McConnell said.

Aides for other top Republicans either declined to comment or did not respond to requests for comment on Sunday.

In addition to saying he was never "briefed or told" about the intelligence report - a formulation that went beyond the White House denial of any formal briefing - Mr Trump also cast doubt on the assessment's credibility, which statements from his subordinates had not.

Specifically, he described the intelligence report as being about "so-called attacks on our troops in Afghanistan by Russians"; the report described bounties paid to Taleban militants by Russian military intelligence officers, not direct attacks. He also suggested that the developments could be a "hoax" and questioned whether The Times' sources - government officials who spoke on condition of anonymity - existed.

US officials said the Russian plot to pay bounties to Taleban fighters came into focus over the past several months after intelligence analysts and Special Operations forces put together key pieces of evidence.

One official said the seizure of a large amount of American cash at one Taleban site got "everybody's attention" in Afghanistan. It was not clear when the money was recovered.

Two officials said the information about the bounty hunting was "well-known" among the intelligence community in Afghanistan, including the CIA's chief of station and other top officials there, like the military commandos hunting the Taleban. The information was distributed in intelligence reports and highlighted in some of them.

The assessment was compiled and sent up the chain of command to senior military and intelligence officials, eventually landing at the highest levels of the White House. The Security Council meeting in March came at a delicate time, as the coronavirus pandemic was becoming a crisis and prompting shutdowns around the country.

A former US official said that the intelligence analyst who briefs the president and the national security adviser, Mr Robert C. O'Brien, working with his chief of staff, Mr Mark Meadows, would have been involved in any decision to brief Mr Trump on Russia's activities. The director of the CIA, Ms Gina Haspel, might have also weighed in, the former official said.

Ms McEnany cited all three of those senior officials in her statement saying the president had not been briefed.

National security officials have tracked Russia's relationship with the Taleban for years and determined that Moscow has provided financial and material support to senior and regional Taleban leaders.

While Russia has at times cooperated with the US and appeared interested in Afghan stability, it often seems to work at crosscurrents with its own national interest if the result is damage to US national interests, said a former senior Trump White House official, who spoke on the condition of anonymity to discuss sensitive security assessments.

Revenge is also a factor in Russia's support for the Taleban, the official said. Russia has been keen to even the scales after a bloody confrontation in 2018 in Syria, when a massive US counterattack killed hundreds of Syrian forces along with Russian mercenaries nominally supported by the Kremlin.

"They are keeping a score sheet, and they want to punish us for that incident," the official said.

Russia and the Taleban have denied the US intelligence assessment.