Ukrainian forces have regained control of almost all of the Kharkiv region in the northeast of Ukraine after launching a counteroffensive against Russia. Russia’s Defense Ministry has acknowledged pulling troops from the city of Izium and other parts of the region. Ukraine is claiming it has recaptured 20 towns and villages over the past 24 hours. But millions were left without power and water on Sunday after Russia bombed key civilian infrastructure facilities in the Kharkiv and Donetsk regions.

The New York Times reports the United States played a key role in helping Ukraine launch the counteroffensive via intelligence sharing and training. One former Obama official said, “These guys have been trained for eight years by Special Ops.” Over the weekend, Ukrainian Foreign Minister Dmytro Kuleba called for allies to send more weapons.

Dmytro Kuleba: “We showed that we can defeat the Russian army. We’re doing it with weapons which were also provided by our partners. I repeat again: The more weapons we receive, the faster we win, the faster this war will end, and we would be able to concentrate on other goals.”

This comes as Ukraine has shut down the last operating reactor at Zaporizhzhia, the largest nuclear power plant in Europe, amid fears that fighting near the Russian-occupied facility could lead to a nuclear catastrophe.