The change was a victory for President Biden and a setback to President Vladimir V. Putin of Russia, who had justified the Ukraine invasion as a warning against NATO’s expansion.
Group of 7 leaders meeting in Germany were receptive to a Biden administration plan to cap the price of Russian oil in world markets, limiting Kremlin revenue.
The area around Sievierodonetsk and Lysychansk is about three-quarters encircled by Russians, leaving only a slender gap there for Ukrainian troops to maneuver.
In another setback for Moscow, top officials from alliance nations met over the weekend in Berlin to discuss admitting Finland and Sweden and supporting Ukraine.