Tensions on the Ukrainian border continue to be fraught, with the US suggesting Moscow is preparing for a “false-flag operation” in order to spark an incursion into neighbouring territory.
The new US intelligence was unveiled after little progress was made in talks between the Kremlin and Washington and its Western allies aimed at heading off the escalating crisis.
Foreign Secretary Liz Truss, appearing to back up the US intelligence, said on Saturday: “Russia is waging a disinformation campaign intended to destabilise and justify an invasion of its sovereign neighbour Ukraine.
“Russia must halt its aggression, de-escalate and engage in meaningful talks.”
Russia's Deputy Foreign Minister Sergei Ryabkov later accused the US and NATO of blackmail and attempting to intimidate the Kremlin, in a move he described as "unacceptable and will not yield results", the Russian Embassy in London tweeted.
In comments earlier tweeted by the Embassy, Mr Ryabkov said the "West is not ready to meet Russia’s proposals halfway" and that the US and NATO "want to discuss security guarantee issues only on terms convenient for them".
Amid the stand-off, Ms Truss’ colleague Defence Secretary Ben Wallace met Nordic partners this week, including Finland which shares a border with Russia.
He said an invasion by Russia into Ukraine would violate the “most basic freedoms and sovereignty” and warned the Kremlin there would be “consequences” of any aggression towards its neighbour.
On Monday, he fired a shot across the bows, telling an event in London that Britain would “stand up to bullies”, no matter how far away the conflict.
Mr Wallace met with ministers in Sweden, Finland and Norway to discuss Russia’s continued aggression and military build-up on Ukraine’s border, with some 100,000 troops amassed at the divide, said the Ministry of Defence (MoD).
The defence secretary said: “The UK and our Nordic partners are united in our approach to upholding European security.
“My discussions this week have been directly about deepening bilateral relations, shared security and the consequences of Russian aggression towards Ukraine.
“Our discussions were clear that a Russian invasion of Ukraine would be a strategic mistake, violating the most basic freedoms and sovereignty.
“Britain and the Nordic countries have a long and shared history.
“Our European neighbours and allies remain vital partners as we work together to defend our common values, counter shared threats and build resilience in our neighbourhood, the UK will always stand with them.”
Labour said the threats facing Ukraine must be met with “strength and solve” by Nato and Europe, with shadow defence secretary John Healey having visited the country this week.
“The Western allies must work hard to maintain their deterrent pressure on Russia and stand by Ukraine,” said the senior opposition MP.
Giving details of the Defence Secretary’s three-day visit, the MoD said that Mr Wallace met with his Swedish counterpart, defence minister Peter Hultqvist, before travelling to Finland to hold discussions with President Sauli Niinisto, foreign minister Pekka Haavisto and defence minister Antti Kaikkonen.
The third leg of his trip saw the Defence Secretary meet with his Norwegian counterpart Odd Roger Enoksen.