As Russia continues to build up its troops along the border with Ukraine, U.S. Secretary of State Antony Blinken said on Sunday that the U.S. and allied nations are prepared to respond if Moscow moves to invade its neighbor. “If a single additional Russian force goes into Ukraine in an aggressive way, as I said, that would trigger a swift, severe and united response from us and from Europe,” Blinken said on CNN’s “State of the Union.” “We’re prepared either way.” He added that while a diplomatic resolution is preferred, “the choice is Vladimir Putin’s.” Western allies have rallied around preventing a Russian attack of Ukraine, but diplomacy and deescalation has been difficult, as Russia continues to push for demands that Western allies are “not by one iota going to compromise on,” including issues like banning Ukraine from joining NATO. The U.K. has promised to enforce severe economic sanctions if Russia attempts to install a “puppet regime” in Ukraine. The Russian foreign ministry is blaming Western allies for “escalating tensions” with Ukraine and spreading “disinformation.”