She aforesaid G7 foreign ministers meeting in port this weekend would placed on a show of unity and illuminate such a move would be a “strategic mistake”.
Ms Truss aforesaid the united kingdom and its allies had to “deter Russia from taking that course of action”.
Tensions ar growing as Moscow amasses troops on Ukraine’s border – however the Kremlin has denied it plans to invade.
Reiterating previous warnings from the America and its allies, Ms Truss aforesaid the G7 “are planning to completely be robust in our stance against aggression… with regard to Ukraine”.
She added: “If Russia were to require that action, it’d be a strategic mistake, and there’ll be severe consequences for Russia.
“And what we’re doing this weekend is functioning with similar allies to spell that out.”
Ukraine shares borders with each the EU and Russia, however as a former Soviet republic it’s deep social and cultural ties with Russia.
However, Russia has suspect country of provocation, and wanted guarantees against eastward nato enlargement and readying of weapons close to its border.
Ahead of the G7 meeting, Ms Truss control talks with Ukrainian government minister Dmytro Kuleba in London.
Asked if she might rule out a military response to Russian aggression, Ms Truss aforesaid the united kingdom was operating with country on “defence and security capability”.
“We are providing them with support,” she said. “We also are operating to assist them with their energy resilience. therefore they don’t seem to be only addicted to Russian energy provides. which is that the approach ultimately that we’ll facilitate support country.”
Ms Truss aforesaid the united kingdom and EU were attempting to confirm Western economies were less addicted to Russian energy.
The foreign secretary aforesaid the Nord Stream a pair of gas pipeline between Germany and Russia would be “a problem” if Russia invaded country.
It would be a difficulty to debate together with her new German counterpart at the G7 talks.
Ms Truss said: “We completely have to be compelled to cut back dependence on Russian gas and energy. And this could be a part of an overall strategy of reducing dependence on non market economies, reducing dependence on malign actors, and ensuring that the accumulation is ready to own that strategic independence it has to survive and thrive.”