President Biden took verbal shots at Russian President Vladimir Putin on Friday during remarks at the White House.
Biden was speaking at a press conference updating the U.S. public on efforts to respond to Hurricane Ian's damage to Florida and South Carolina.
At the end of his remarks, he shifted gears and addressed Russia's referendums to annex Ukrainian territories in the middle of the country's continued invasion.
After Ukraine said it had submitted an "accelerated" NATO application, Biden warned, "I want to say this again. America is fully prepared with our NATO allies to defend every single inch of NATO territory... So Mr. Putin, don't misunderstand what I'm saying. Every inch."
Biden dismissed the referendums as "a sham" and mocked the Russian president's actions as "a sign he is struggling" before announcing new avenues of sanctions to further press Putin and his allies.
Putin formally approved the annexations and came out swinging at the U.S. in an aggressive speech on Friday. He then appeared before thousands at a rally in Moscow's Red Square.
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In a message that was already expected to be hostile, Putin further escalated threats against Ukraine and the West by saying the U.S. had set a "precedent" of nuclear warfare by attacking Japan with atomic bombs during World War II.
"We're announcing new sanctions today, as well, that include new authorities to sanction anyone who provides political or economic support to Russia's fraudulent territorial claims," Biden said in response.
He concluded by stating, "I've been in close touch with our NATO allies, who are united in our resolve to take on his aggression."
Ukrainian President Volodymyr Zelenskyy on Friday said that Kyiv had "accelerated" its application to join the NATO military alliance as Russia moved to annex four Ukrainian regions.
It was not immediately clear how Kyiv has pushed its application along, but Zelenskyy, who has vowed to keep fighting Russia despite its illegal annexation, said that Ukraine has already proven a "compatible" partner to NATO.
Zelenskyy has already said that he will not engage with Russia in peace talks if they attempt to unilaterally seize Ukrainian territory.
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"De facto, we have already proven compatibility with alliance standards. They are real for Ukraine — real on the battlefield and in all aspects of our interaction," he said. "We trust each other, we help each other, and we protect each other. This is the alliance."
Biden also alleged that the damage to the Nord Stream pipeline was a "deliberate act of sabotage," adding that the U.S. will be sending divers to "find out exactly what happened."
Fox News' Caitlin McFall contributed to this report.