US President Joe Biden has been sounding the alarm about the buildup of Russian troops along the border with Ukraine. Now, he has taken those concerns directly to Russian President Vladimir Putin.

The two leaders spoke for two hours on a video call. It was their first conversation since July.

Russia has amassed more than 90,000 soldiers along the border. Leaders in Ukraine and in NATO countries are worried that they are preparing to invade.

The White House said Biden expressed "deep concerns" about the escalation of forces around Ukraine. He said the US and its European allies would respond to a continued buildup with "strong economic measures" and other actions.

Putin told Biden that NATO was building up its own military power near Russia's borders. The Kremlin released a statement saying he wants a guarantee against NATO's further eastward expansion.

The two leaders agreed to continue talks over the issue.