Former F1 world champion Sebastian Vettel has become the first driver to boycott the Russian Grand Prix.
Vladimir Putin launched a 'full scale invasion' of Ukraine in the early hours of Wednesday morning, leaving an uncertain outlook across Europe and the wider world.
Formula One are due to return to Russia in the 2022 season - but Vettel, who won four successive titles between 2010 and 2013, says he will not be present should that be the case.
"I should not go, I will not go," he said. "People are being killed for stupid reasons. A very strange and mad leadership."
Current world champion Max Verstappen also hinted he may not travel, should the race go ahead.
LIVE: Follow our latest updates from the Russia-Ukraine conflict here.
"When a country is at war, it is not right to race there," he said.
UK Prime Minister Boris Johnson has warned of 'a tidal wave of violence' from Russia against Ukraine.
"Innumerable missiles and bombs have been raining down on an entirely innocent population. A vast invasion is under way, by land, by sea and by air," he said.
"Our mission is clear. Diplomatically, politically, economically and eventually militarily this hideous and barbaric venture of Vladimir Putin must end in failure.
Johnson spoke to Ukrainian President Volodymyr Zelensky in the early hours of Thursday, before chairing an emergency COBRA meeting at 7.30am.
Ahead of the meeting, he said: "President Putin has chosen a path of bloodshed and destruction by launching this unprovoked attack on Ukraine. The UK and our allies will respond decisively."
Nato Secretary-General Jens Stoltenberg added: "This is a grave moment of the security of Europe. Russia's unprovoked and unjustified attack on Ukraine is putting countless lives at risk.
"This is a deliberate, cold-blooded and long planned invasion.
"It is a blatant violation of international law, an act of aggression against a sovereign, independent and peaceful country and a serious threat to Euro-Atlantic security."
