Russian forces have begun an assault on the town of Sudzha, the main population center in the Kursk region that was captured by Ukraine last year, a top Russian commander said on Tuesday. The advance puts Moscow on the verge of ending the first invasion of Russian territory since World War II.

Ukraine’s presence in Russia’s Kursk region has deteriorated sharply, with the advance threatening Kyiv’s sole territorial bargaining counter at a crucial time in the war.