British prime minister Boris Johnson has said evidence suggests Russia is planning “the biggest war in Europe since 1945” in an interview with the BBC from Munich’s security conference.

The prime minister said US President Joe Biden had told Western leaders that intelligence suggested Russian forces intend to launch an invasion that will encircle Ukrainian capital, Kyiv.

According to Johnson, Russian troops were not just planning on entering Ukraine from the east, via Donbas, but down from Belarus and the area surrounding Kyiv.

All the signs are that the plan has already in some senses begun.

People need to understand the sheer cost in human life that could entail.

I’m afraid to say that the plan we are seeing is for something that could be really the biggest war in Europe since 1945 just in terms of sheer scale.”

People need to not only consider the potential loss of life of Ukrainians, but also of “young Russians”, Johnson added.

Russia nuclear drill raise tension

Hundreds of artillery shells exploded along the contact line between Ukrainian soldiers and Russia-backed separatists, and thousands of people evacuated eastern Ukraine, further increasing fears Sunday that the volatile region could spark a Russian invasion.

Western leaders warned that Russia was poised to attack its neighbor, which is surrounded on three sides by about 150,000 Russian soldiers, warplanes and equipment. Russia held nuclear drills Saturday and conducted conventional exercises in neighboring Belarus, and has ongoing naval drills off the coast in the Black Sea.

The United States and many European countries have alleged for months that Russia is trying to create pretexts to invade. They have threatened massive, immediate sanctions if it does.