President Joe Biden said Wednesday he had warned his Russian counterpart Vladimir Putin of unprecedented US sanctions if Russia attacks Ukraine.
A day after talking for two hours by video link, Biden said he had told Putin the United States would retaliate with sanctions "like none he's ever seen" in the event of a Russian assault on Ukraine.
"I made it very clear, if in fact he invades Ukraine, there will be severe consequences, severe consequences -- economic consequences like none he's ever seen or ever have been seen," Biden told reporters at the White House.
Biden said that in addition to economic measures, a new Russian attack on Ukraine would trigger a bolstered US military presence on the territory of NATO allies in eastern Europe.
"We would probably be required to reinforce our presence in NATO countries to reassure particularly those in the eastern flank. In addition to that, I made it clear that we would provide a defensive capability to the Ukrainians as well," he said.
However, Biden said that sending US troops to defend Ukraine from Russia is "not on the cards," because the country is not part of NATO.
"The idea the United States is going to unilaterally use force to confront Russia invading Ukraine is not on the cards right now," Biden said. "We have a moral obligation and a legal obligation to our NATO allies under Article Five. It's a sacred obligation. That obligation does not extend to... Ukraine."
Biden said he was sure Putin understood the US position after their talks.
"I am absolutely confident he has the message," he said.