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.

Russian special forces walked inside a gas pipeline to strike Ukrainian units from the rear in the Kursk region, Ukraine’s military and Russian war bloggers reported, as Moscow claimed fresh gains in its push to recapture parts of the border province that Kyiv seized in a shock offensive.