The White House is under pressure to explain how much the administration knew about allegations Russia offered the Taliban bounties to kill US troops.
Officials have insisted that President Donald Trump was not “personally” informed of the alleged plot in Afghanistan in 2019.
But reports say the president received a written briefing earlier this year.
There is concern that Mr Trump might have had access to information about threats to US forces but did not act.
The intelligence reportedly arrived amid US attempts to negotiate a peace deal to end the 19-year war in Afghanistan and while Mr Trump sought to improve relations with Russian President Vladimir Putin.
Reports by The New York Times, Washington Post and Wall Street Journal, quoting unnamed US officials, said a Russian military intelligence unit had offered Taliban-linked militants bounties to kill US troops in Afghanistan.
Twenty American troops died in Afghanistan in 2019, but the New York Times said it was not clear which deaths were under suspicion.
Russia denied the initial reports, while the Taliban said it had not done any deal with Russian intelligence.
The allegations come as Mr Trump seeks re-election in the November poll.
Moscow maintains close links with the Taliban, as it sees the US involvement in Afghanistan winding down, the BBC’s diplomatic correspondent Jonathan Marcus says.
He says Russia is also waging a “grey” or undeclared war against the West. Under President Vladimir Putin, the Kremlin has smarted from every perceived indignity suffered since the fall of the Soviet Union. It was US support for Afghan irregular fighters that contributed to Moscow’s forced withdrawal from Afghanistan in the 1980s.
CNN and the Associated Press have also reported that the president received the intelligence in a written briefing earlier this year, without specifying when. Mr Trump is said to largely ignore the President’s Daily Brief, relying more on oral briefings by intelligence officials a few times a week.
White House Press Secretary Kayleigh McEnany did not answer when asked by reporters whether the information had been included in the president’s written briefing, saying only that Mr Trump had not been “personally briefed”.
Ms McEnany also said there was “no consensus within the intelligence community” about the assessment. But former intelligence officials told US media that, in previous administrations, claims of such importance would be reported to the president, even if the evidence had not been fully established.
Eight Republican Congress members attended a White House briefing led by Director of National Intelligence John Ratcliffe, White House Chief of Staff Mark Meadows and National Security Adviser Robert O’Brien on Monday.
Some expressed alarm about the claims, calling for action against Russia and President Putin to be taken if the intelligence reports, currently under review, were confirmed.
Writing on CNN, Bernstein – one of the journalists who investigated the Watergate scandal in the 1970s – said there were special concerns over “[Mr] Trump’s deference to [Mr] Putin”, with the US president “inordinately solicitous of [Mr] Putin’s admiration” while ignoring important matters on the bilateral agenda.
In an interview to promote his book, Mr Bolton said of Mr Trump: “I think Putin thinks he can play him like a fiddle.”
What is the context?
The unnamed officials cited by the New York Times’ initial report said US intelligence agencies had concluded months ago that a unit of Russia’s GRU military intelligence agency had sought to destabilise its adversaries by covertly offering bounties for successful attacks on coalition forces.
Islamist militants, or armed criminal elements closely associated with them, were believed to have collected some money, the newspaper said.
The officials quoted by the New York Times said the White House’s National Security Council had considered how to respond, including imposing an escalating raft of sanctions against Russia.
According to the Times story on Friday, President Trump was briefed on the reports in March. Mr Trump denied having been briefed, writing on Twitter on Sunday that neither he nor Vice-President Mike Pence had been told “about the so-called attacks on our troops in Afghanistan by Russians”.
Sergei Zhirnov, a former agent of Russia’s Foreign Intelligence Service (SVR), told BBC Russian that the GRU’s actions could be a part of a larger game between Mr Putin and Mr Trump unfolding in the global arena.
“The GRU is a massive machine, which works towards making war. Putin likes to flex his muscles when there is no chance of retribution,” said Mr Zhirnov.