Russia is planning to fabricate a pretext for an invasion of Ukraine, by falsely blaming Ukrainian military for an attack on Russian-backed separatists or Russia itself, US officials say.
One option Russia is said to be considering is to stage and film a fake attack, with graphic images of an explosion showing numerous casualties.
The US and Nato are concerned at the massing of Russian forces near Ukraine.
Russia denies planning to invade, saying the troops are there for drills.
They currently number about 100,000.
The tensions come eight years after Russia annexed Ukraine’s southern Crimea peninsula and backed a bloody rebellion in the eastern Donbas region.
Senior US administration officials said the alleged operation, planned by Russian security services, would show images of civilian casualties in Donbas, eastern Ukraine, in order to generate outrage against the Ukrainian authorities.
This could then be used to justify an attack on Ukraine, the officials said.
The officials said the plan could involve staging and filming a faked attack.
It would show corpses and destroyed locations, faked Ukrainian military equipment, Turkish-made drones and actors playing Russian-speaking mourners, they said.
But the officials stressed that this was only one of the options Russia was considering, and said they were publicising it in an effort to “dissuade Russia from its intended course of action”.
News of the alleged plot came a day after the US said it was sending more troops to Nato allies in Europe.
Russia said the move was “destructive” and showed that its concerns about Nato’s eastward expansion were justified.
Rivalry between Russia and the US, which still possess the world’s biggest nuclear arsenals, dates back to the Cold War (1947-89). Ukraine was then a crucial part of the communist Soviet Union.