British foreign secretary warns Moscow that any further military incursion into Ukraine would bring "massive consequences".
Britain has warned Moscow that it was working with Western partners on high-impact sanctions targetting Russia's financial sector should it invade Ukraine.
"We will not accept the campaign Russia is waging to subvert its democratic neighbours," Foreign Secretary Liz Truss told parliament on Thursday.
"They have falsely cast Ukraine as a threat to justify their aggressive stance."
"Russia is the aggressor here," Truss said. "NATO has always been a defensive alliance."
Russia has massed some 100,000 troops near Ukraine's border and though Moscow says it has no plans to invade its neighbour, President Vladimir Putin has demanded legally-binding guarantees that NATO will not expand further eastwards.
Russia annexed the Black Sea peninsula of Crimea from Ukraine in 2014, drawing sanctions and condemnation from the West. Kyiv wants the territory back.
Truss said that any further military incursion into Ukraine by Russia would bring "massive consequences, including coordinated sanctions to impose a severe cost on Russia's interests and economy."
Britain, Truss said, was opposed to the Nord Stream 2 pipeline under the Baltic Sea.
Putin says NATO's expansion eastwards since the 1991 fall of the Soviet Union is a threat to Russia which, he says, has nowhere left to retreat to. He has warned the West against ignoring his concerns.