Allies watch for Kremlin attempt to justify Ukraine invasion

The U.S. issued some of its starkest, most detailed warnings yet about how a Russian invasion of Ukraine might unfold, and its Western allies went on high alert for any attempts by the Kremlin to create a false pretext for a new war in Europe.

U.S. President Joe Biden sounded unusually dire Thursday, as he warned that Washington saw no signs of a promised Russian withdrawal, but instead saw more troops moving toward the border with Ukraine, indicating Moscow could invade within days.

"Every indication we have is they're prepared to go into Ukraine, attack Ukraine," Biden told reporters at the White House.

He said the U.S. has "reason to believe" that Russia is "engaged in a false flag operation to have an excuse to go in," but he did not provide details.

Western fears focus on an estimated 150,000 Russian troops, about 60% of Russia's overall ground forces, posted around Ukraine's borders. The Kremlin insists it has no plans to invade, but it has long considered Ukraine part of its sphere of influence and NATO's eastward expansion an existential threat. A key demand in this crisis is that NATO promise never to allow Ukraine to join.

Biden planned to speak by phone Friday with trans-Atlantic leaders about the Russian military buildup and continued efforts at deterrence and diplomacy.

U.S. Secretary of State Antony Blinken revealed some conclusions of U.S. intelligence, part of a strategy designed to expose and pre-empt any invasion planning. The U.S. has declined to reveal much of the evidence underlying its claims.

Blinken told diplomats at the U.N. Security Council that a sudden, seemingly violent event staged by Russia to justify an invasion would kick off the assault. Blinken mentioned a "so-called terrorist...