WILMINGTON, Del. (AP) — President Joe Biden has warned Russia’s Vladimir Putin that the U.S. could impose new sanctions against Russia if it takes further military action against Ukraine. Putin has responded that such a U.S. move could lead to a complete rupture of ties between the nations. The two leaders spoke frankly for nearly an hour amid growing alarm over Russia’s troop buildup near Ukraine. Putin’s foreign affairs adviser says further U.S. sanctions “would be a colossal mistake that would entail grave consequences.” The White House says Biden made clear that the U.S. and its allies “will respond decisively if Russia further invades Ukraine.”