President Joe Biden and Russian President Vladimir Putin speak on the phone as tension mounts over the situation on Ukraine’s border

President Biden and Russian President Vladimir Putin spoke on the phone for nearly an hour amid growing concern over Moscow’s military buildup along the Ukrainian border. The two world leaders exchanged warnings, with President Biden telling Putin that the U.S. will act “decisively” if Russia invades Ukraine. CBS News political contributor and White House reporter for The Washington Post, Sean Sullivan, joins CBSN to discuss the high-stakes call.