"Reports over the weekend claimed that 800 Russian special forces had crawled for 15 kilometers through an unused section of pipeline, which once carried Russian gas to Europe via Ukraine, in order to carry out a sneak attack on Ukrainian forces in Sudzha."

https://www.themoscowtimes.com/2025/03/11/russian-army-reports-major-advances-in-kursk-region-after-operation-pipeline-a88315