US President Biden

Ukraine tension: Biden says he thinks Putin will 'move in'

Asked at a news conference about the threat of a Russian invasion, he said: "My guess is he will move in, he has to do something."

But he warned that the Russian leader would pay a "serious and dear price" for "testing" the West.

Moscow denies planning to attack or invade but has built up its forces.

It is estimated to have about 100,000 troops close to Ukraine's borders.