Boris Johnson will "ramp up deterrence to avoid bloodshed" between Russia and Ukraine with a visit to the region in the coming days amid rising tensions, it is understood.
The Prime Minister is determined to "accelerate diplomatic efforts" during a trip in the coming days and will speak to Russian President Vladimir Putin in a phone call.
It comes after he asked defence and security chiefs to consider further defensive military options in Europe during a high-level intelligence briefing on the situation last week.
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Fresh deployments and further NATO support are being considered by Mr Johnson this weekend.
A Downing Street spokeswoman said: "The Prime Minister is determined to accelerate diplomatic efforts and ramp up deterrence to avoid bloodshed in Europe.
"He will reiterate the need for Russia to step back and engage diplomatically when he speaks to President Putin this week."
The Foreign Office is also expected to announce tougher sanctions on Monday, meaning the UK can target Russia's strategic and financial interests.
Watch: Where is NATO deployed in Europe?
Tensions have soared in recent weeks, as the US and its NATO allies expressed concern that a build-up of about 100,000 Russian troops near Ukraine signalled that Moscow planned to invade its ex-Soviet neighbour.
Russia is against future NATO membership expansion to include Ukraine.
Since 2015, British military personnel on Operation Orbital have helped support Ukraine against Russian aggression, training thousands of students, some of whom are volunteers, in key medical and infantry skills.
The show of support followed Russia's illegal annexation of Crimea in 2014.
UK forces are also deployed to Estonia on Operation Cabrit, one of four NATO battlegroups in the Baltic states and Poland.