President Joe Biden was "crystal clear" on the consequences Russia will face should Moscow decide to invade Ukraine, National Security Advisor Jake Sullivan said in a press briefing following a two-hour-long video call between Biden and Russian President Vladimir Putin on Tuesday.

"[Biden] told President Putin directly that if Russia further invades Ukraine, the United States and our European allies would respond with strong economic measures," said Sullivan. "We would provide additional defensive material to the Ukrainians above and beyond that which we are already provided. And we would fortify our NATO allies on the eastern flank with additional capabilities in response to such an escalation."

The virtual summit came just days after an explosive intelligence analysis, first reported by The Washington Post, revealed that Moscow could be planning to launch a 175,000-troop offensive against Ukraine early next year. Leading up to the talk, Putin had warned Biden against crossing his "red lines" when it comes to Ukraine, seeking a guarantee that NATO forces would neither expand into Eastern Europe nor allow Ukraine to join as a member.

Biden's response to that? "I don't accept anybody's red lines."