Ukraine has launched a new offensive in Russia’s region of Kursk. But it’s not clear why exactly Ukraine is waging a new assault in Kursk, and why now.

Ukrainian President Volodymyr Zelenskyy said Monday that some 38,000 Russian troops have been killed or wounded fighting in Russia's western Kursk region since August, with Kyiv now launching a fresh offensive in the border region.

Russia said on Monday its forces had made important gains in eastern Ukraine while continuing to fend off a new Ukrainian offensive inside the Kursk region of western Russia, where a second day of fierce fighting was under way.

Ukraine has largely been driven out of Kurakhove, a battered but strategic town in the Donbas, Russia said. Kyiv’s forces were pressing a renewed offensive in southern Russia.

Ukraine launched a new offensive in Russia's Kursk region Sunday, Moscow and Kyiv said. Ukrainian forces had captured about 500 square miles of the western Russian province in a surprise incursion in August, but Russian and North Korean troops are believed to have retaken 40-50% of that area.

Russian forces continue to make costly but consistent gains in the Donetsk region in eastern Ukraine. They are steadily grinding down a pocket of resistance around the town of Kurakhove and are also fighting to envelop the larger nearby city of Pokrovsk, Ukrainian soldiers and officials said.

Russia has claimed that its forces captured a battered but strategic town in Ukraine’s eastern Donetsk region, a day after Kyiv launched a counterattack in the Russian region of Kursk.