President Joe Biden on Tuesday delivered a warning to Russian President Vladimir Putin over a potential Russian invasion of Ukraine, according to a White House readout of a video call between the two leaders. Biden "voiced the deep concerns of the United States and our European Allies about Russia's escalation of forces surrounding Ukraine and made clear that the U.S. and our Allies would respond with strong economic and other measures in the event of military escalation," the White House said in a statement. The American president also "reiterated his support for Ukraine's sovereignty and territorial integrity and called for de-escalation and a return to diplomacy," the statement said. "The two presidents tasked their teams to follow up, and the U.S. will do so in close coordination with allies and partners." Biden had been expected to deliver a message along those lines as he seeks a diplomatic solution to deal with the tens of thousands of Russian troops massed near the Ukraine border.