Prime Minister Boris Johnson says Britain is considering deploying fighter jets and warships to Southeastern Europe, amid growing tensions between Moscow and the West over Ukraine.
"We are considering deploying RAF Typhoon fighters and Royal Navy warships to protect southeastern Europe," Johnson wrote in The Times on Monday.
The British premier added that his country was also preparing to reinforce the British-led NATO battlegroup in Latvia and Estonia.
"NATO allies are agreed that we are willing to send more forces to guarantee the security of our allies on the eastern flank. The foreign ministers of Latvia and Estonia have called for extra support due to the Russian military build-up in Belarus. We stand ready to provide it," Johnson said.
He said the UK "will not flinch" over Ukraine and sanctions would be introduced if Russia invaded.
The West will do more to help Ukraine defend itself, he said.
Relations between Russia and the West have hit a new low in recent weeks. The United States, its NATO allies, and Ukraine have accused Russia of amassing troops near Ukraine's border for a possible invasion. Moscow rejects the allegation and insists that deployments are defensive in nature.
Last week, a Royal Air Force spokesman confirmed to that UK fighter jets had intercepted and escorted four Russian Tu-95 bombers passing through the country's "zone of interest."
NATO members Britain and Poland have agreed to directly send arms to Ukraine, including handguns, ammunition, and anti-tank weapons. The US military has also placed 8,500 troops on heightened alert to prepare for deployment in Eastern Europe and bolster the NATO presence in the region. The US State Department has also approved shipments of US-made missiles and other weapons from NATO allies Lithuania, Latvia, and Estonia to Ukraine.
The US and the European Union have threatened tough sanctions against the Kremlin in the event of an attack on or invasion of Ukraine.
American and Russian diplomats held talks to resolve the crisis over Ukraine in January but failed to make a breakthrough. However, they agreed to continue the talks.
Russia has demanded legally binding guarantees from NATO that it will halt its eastward expansion and return to its 1997 borders. Moscow also demanded that the military alliance never admit Ukraine as a member.