Any renewed Russian aggression in Ukraine would trigger "serious consequences", U.S. Secretary of State Antony Blinken said on Tuesday.
Blinken spoke at a news conference in Riga where he is attending a meeting of NATO foreign ministers due to discuss Russia's massing of troops on its border with Ukraine.
Blinken called the Russian troop movements "unusual" and added any escalatory actions by Russia would be of "great concern" to the United States.