The US on Thursday accused the Kremlin of an elaborate plot to fabricate an attack by Ukrainian forces that Russia could use as a pretext to take military action against its neighbour.
Pentagon spokesman John Kirby said the plan included production of a graphic propaganda video that would show staged explosions and use corpses and actors depicting grieving mourners.
Russia is formulating several options to give it an excuse for an invasion of Ukraine, Mr Kirby said, without presenting any evidence.
“One option is the Russian government, we think is planning to stage a fake attack by Ukrainian military or intelligence forces against Russian sovereign territory, or against Russian-speaking people, to therefore justify their action as part of this fake attack,” Mr Kirby said.
The White House in December accused Russia of developing a “false-flag” operation to create a pretext for an invasion.
Britain recently named specific Ukrainians it accused of having ties to Russian intelligence officers plotting to overthrow Ukrainian President Volodymyr Zelenskiy.
The US also released a map of Russian military positions and detailed how officials believe Russia will try to attack Ukraine with as many as 175,000 troops.
“We’ve seen this kind of activity by the Russians in the past, and we believe it’s important when we see it like this, and we can, to call it out,” Mr Kirby told reporters at the Pentagon.
The US has not provided detailed information backing up the intelligence findings.
Jonathan Finer, the US deputy national security adviser, told NBC News that the US did not know for sure if Russia was going to proceed with the plan.
“We know that this is an option under consideration,” he said.
It “would involve actors playing mourners for people who are killed in an event that [Russia] would have created themselves … [and] deployment of corpses to represent bodies purportedly killed".
Russia has accused the US of ramping up tension and ignoring Moscow's calls to ease a standoff over Ukraine, a day after Washington announced it would send about 3,000 extra troops to Poland and Romania.
Moscow has denied plans of an invasion but has amassed thousands of troops on its border with Ukraine.
UK Foreign Secretary Liz Truss said the US disclosures represented “clear and shocking evidence of Russia’s unprovoked aggression and underhand activity to destabilise Ukraine".
“The UK and our allies will continue to expose Russian subterfuge and propaganda and call it out for what it is. The only way forward is for Russia to de-escalate, desist and commit to a diplomatic pathway,” Ms Truss said.