Russian President Vladimir Putin's speech on Wednesday was a worrying escalation and the threats he made must be taken seriously, British foreign office minister Gillian Keegan told Sky News.
Putin ordered Russia's first military mobilisation since World War Two, warning the West that if it continued what he called its "nuclear blackmail" that Moscow would respond with the might of all its vast arsenal.
"Clearly it's something that we should take very seriously because, you know, we're not in control - I'm not sure he's in control either, really. This is obviously an escalation," Keegan said.
"It is chilling ... It's a serious threat, but one that has been made before," she told the BBC in a separate interview.
Putin restated his objective was to "liberate" eastern Ukraine's Donbas industrial heartland and that most people in the region did not want to return to what he called the "yoke" of Ukraine.
"The overall address clearly was more of Putin's lies, it was a rewriting of history," Keegan said. (Reporting by William James, editing by Paul Sandle, Andrew Heavens and Mark Heinrich)