A US official said: “As part of its plans Russia is laying the groundwork to have the option of fabricating a pretext for invasion, including through sabotage activities and information operations, by accusing Ukraine of preparing an imminent attack against Russian forces in eastern Ukraine.”
Another official told CNN: “The Russian military plans to begin these activities several weeks before a military invasion, which could begin between mid-January and mid-February. We saw this playbook in 2014 with Crimea.”
It followed comments on Thursday by Jake Sullivan, Joe Biden’s national security adviser.
Mr Sullivan said: “Our intelligence community has developed information, which has now been downgraded, that Russia is laying the groundwork to have the option of fabricating the pretext for an invasion.
“We saw this playbook in 2014. They are preparing this playbook again and we will have further details on what we see as this potential laying of the pretext to share over the course of the next 24 hours.”
Speaking in Washington an aide to Ukraine’s president Volodymyr Zelensky said he has proposed three-way talks with Joe Biden and Vladimir Putin amid fears of invasion.
Andriy Yermak said: “President Zelensky proposed to President Biden and we think it can be worked to organise a trilateral meeting, maybe by videoconference, between President Biden, President Zelensky and President Putin.
“We are still waiting for the reaction on this, I think, from the Russian side. But our American partners take our proposal with some interest.”
Mr Biden and Putin have spoken twice by telephone amid the tensions.
Mr Biden has warned of devastating economic sanctions if Russia invades.