Russia this week sent a formal diplomatic note to the United States warning that U.S. and NATO shipments of the “most sensitive” weapons systems to Ukraine were “adding fuel” to the conflict there and could bring “unpredictable consequences.”

The diplomatic démarche, a copy of which was reviewed by The Washington Post, came as President Biden approved a dramatic expansion in the scope of weapons being provided to Ukraine, an $800 million package including 155 mm howitzers — a serious upgrade in long-range artillery to match Russian systems — coastal defense drones and armored vehicles, as well as additional portable antiaircraft and antitank weapons and millions of rounds of ammunition…

“What the Russians are telling us privately is precisely what we’ve been telling the world publicly — that the massive amount of assistance that we’ve been providing our Ukrainian partners is proving extraordinarily effective,” said a senior administration official, who spoke on the condition of anonymity about the sensitive diplomatic document.