'Every indication' Russia prepared to attack Ukraine: Biden

U.S. President Joe Biden warned Thursday that Russia could still invade Ukraine within days, and the No. 2 diplomat at the U.S. Embassy in Moscow was expelled as tensions flared anew in the worst East-West standoff in decades.

NATO allies accused Russia of misleading the world by saying it was returning some troops to their bases but instead moved in thousands of new ones. The pullout pledge was among Russian gestures this week that briefly cooled temperatures. Russia is believed to have some 150,000 military forces around Ukraine's borders, raising fears of a new war in Europe.

Tensions also spiked Thursday along the line that separates Ukrainian forces from Russia-backed separatists in the country's east, with both sides accusing each other of intensive shelling in a long-simmering conflict that has killed 14,000 people.

In a surprise blow to diplomacy, Russia ordered the deputy chief of mission at the U.S. Embassy in Moscow, Bart Gorman, to leave the country, the State Department said. It called the move "unprovoked" and "an escalatory step." Russia did not say why he was expelled.

Concerns escalated in the West over what exactly Russia is doing with its troops around Ukraine -- including an estimated 60% of the overall Russian ground forces -- and about President Vladimir Putin's overall intentions.