White House national security adviser Jake Sullivan said on Sunday that Russia could invade Ukraine “any day” now. Sullivan, who is a senior adviser to the Biden administration, warned that if war does break out, “it will come at an enormous human cost to Ukraine,” but didn’t address reports that the White House apparently believes a Russian invasion could involve up to 50,000 casualties, as well as a fast capture of Kyiv. Sullivan added that an invasion would come at a “strategic cost” for Russia as well. “It could happen as soon as tomorrow or it could take some weeks yet… [Putin] has put himself in a position with military deployments to be able to act aggressively against Ukraine at any time now,” Sullivan said. Moscow has denied it has plans to invade Ukraine even as it continues to amass Russian troops on the border.