Britain's Prime Minister Boris Johnson speaks with members of the media during a visit to Warszawska Brygada Pancerna military base near Warsaw, Poland February 10, 2022. Daniel Leal/Pool via REUTERS
Britain's Prime Minister Boris Johnson speaks with members of the media during a visit to Warszawska Brygada Pancerna military base near Warsaw, Poland February 10, 2022. Daniel Leal/Pool via REUTERS Reuters / POOL

British Prime Minister Boris Johnson said on Saturday that if Western nations failed to fulfil their promises to support Ukraine's independence, it would have damaging consequences worldwide, including for Taiwan.

Russian troops are massed near Ukraine's borders and President Vladimir Putin has launched exercises by strategic nuclear missile forces, but Russia rejects Western concerns that it is poised to invade.[L1N2UU05Z]

"We do not fully know what President Putin intends, but the omens are grim," Johnson told a security conference in Munich.

"If Ukraine is endangered, the shock will echo around the world. And those echoes will be heard in east Asia, will be heard in Taiwan," he added. "People would draw the conclusion that aggression pays, and that might is right."

China views Taiwan as part of its territory, and has not ruled out the use of force to regain control of the island, which has governed itself since 1949.

Johnson said Western nations had repeatedly told Ukraine that they would support its independence.

"How hollow, how meaningless, how insulting those words would seem, if at the very moment when their sovereignty and independence is imperilled, we simply look away," he said.

On Tuesday, Britain said it could block Russian companies from raising capital in London and has passed legislation to widen sanctions on Russian businesses and individuals if the country invades Ukraine.

"We will sanction Russian individuals and companies of strategic importance to the Russian state and we will make it impossible for them to raise finance on the London capital markets," Johnson said.

Europe must also wean itself off Russian oil and gas supplies to stop being at the risk of being blackmailed, he added.

Johnson predicted Russia would pay a heavy military price if it invaded Ukraine.

"I fear that a lightning war would be followed by a long and hideous period of reprisals and revenge and insurgency. And Russian parents would mourn the loss of young Russian soldiers," he said.