U.S. President Joe Biden told Russian President Vladimir Putin in a video call on Tuesday that there’ll be strong economic and other sanctions should Russia invade the Ukraine and start a military conflict.

The leaders held two hours of virtual talks on Ukraine and other disputes regarding U.S-Russia relations, which have sunk to their lowest since the end of the Cold War.

The Kremlin, has denied harboring any intention to attack Ukraine. It says the 90 thousand troops near the border is merely defensive.

Biden reiterated U.S. support for Ukraine’s sovereignty and territorial integrity, and called for de-escalation and diplomacy.

Both sides say they hope the two leaders can hold an in-person summit to discuss ties between the two nations, which have long-standing differences over Syria, U.S. economic sanctions and alleged Russian cyber attacks on U.S. companies.