The United States said Thursday it had intelligence that showed Russia is planning to create a video depicting a fake Ukrainian attack, that it could release in order to justify its own invasion of Ukraine.
One of a number of options Russia has been allegedly planning, U.S. officials said, was to "stage a fake attack" against Russia or Russian-speaking people.
"As part of this fake attack, we believe that Russia would produce a very graphic propaganda video, which would include corpses, and actors that would be depicting mourners, and images of destroyed locations as well as military equipment," Pentagon spokesman John Kirby said.
The United States took the rare step of making this intelligence public in order to dissuade Russia from moving forward or, if it did move forward, to make it more difficult for it to spread disinformation after the fact, according to Jon Finer, the principal deputy U.S. national security adviser.
"We don't know definitively that this is the route they're going to take," Finer said in an interview with MSNBC.
"But we know that this is an option under consideration," he continued, "that would involve, you know, actors playing mourners for people who are killed in an event that they would have created themselves, that would involve the deployment of corpses to represent bodies purportedly killed in -- people reportedly killed in an incident like this."
The U.K. said later Wednesday that it had conducted its "own analysis of the intelligence," and that it had "high confidence that Russia is planning to engineer a pretext blaming Ukraine in order to justify a Russian incursion."
“This is clear and shocking evidence of Russia’s unprovoked aggression and underhand activity to destabilize Ukraine," Britain's foreign secretary, Liz Truss, said.
It is not the first time in recent weeks that the United States had accused Russia of "fabricating a pretext" to justify invading Ukraine.
The Kremlin on Wednesday dismissed the new allegations.
"This is not the first such promise," Kremlin spokesman Dmitry Peskov said, according to the Russian state news agency TASS "Earlier, similar things were also voiced. But nothing ever occurs."
Last month, the White House said the U.S. had intelligence that Russia had prepositioned a group of operatives in eastern Ukraine in order to create a "false-flag operation" there. The administration said the group was trained in urban warfare and the use of explosives.
A spokesperson for the White House's National Security Council declined to say whether those the United States is accusing of being involved in creating a fake video were part of this same group.
The U.S. believes Russia has already recruited the people who’d be involved with the fake "attack" video and that “Russian intelligence is intimately involved in this effort," according to the senior administration official.
The U.S. thinks that “the military equipment used in this fabricated attack will be made to look like it is Ukrainian or from allied nations” – and that it was “possible” that Bayraktar drones, which Ukraine has, would be used to make it look like Ukraine carried out the attack, according to the official.
U.S. officials have repeatedly said, as recently as Wednesday, that they do not believe Russia's President Vladimir Putin had yet decided whether to invade Ukraine.
But if he did want to move forward, the senior administration official said, one trigger could be Russia recognizing separatist regions in Ukraine as independent, rather than as part of Ukraine. Russia's parliament is advancing legislation that would do so.
The U.S. believes that if Russia formally recognized the regions as independent, Russia could then release the video showing a fake Ukrainian "attack" – that it could portray as in response to the independence recognition – or Russia could just invade without releasing the video, according to another administration official.
“In line with its previous interventions, Russia would portray its actions as defending ethnic Russians and coming at the request of a sovereign government for assistance," the senior administration official said.
Karen Travers reports for ABC Audio:
ABC News' Matt Seyler, Patrick Reevell and Christine Theodorou contributed to this report.