A White House official on Friday confirmed that Russia has sent a formal diplomatic note to the United States saying weapons shipped to Ukraine from the U.S. and NATO were "adding fuel" to the conflict.
The note, reported by The Washington Post, said deliveries of the "most sensitive weapons" could result in "unpredictable consequences" for the U.S.
Biden on Wednesday authorized an additional $800 million in weapons for Ukraine.
For more on this story, go to NBC News.
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