Russia Attempts to Infiltrate Ukraine Through Pipeline from Kursk

Key Points:

• Russian forces have twice attempted to infiltrate Ukraine’s northern Sumy region via the Brotherhood natural gas pipeline crossing from Russia’s Kursk region in the past ten days, according to the Institute for the Study of War (ISW).
• Ukrainian forces intercepted these attempts, ambushing a 10-man Russian sabotage group on September 12 and later killing 29 Russian soldiers and wounding three in a larger engagement near Mala Korchakivka on September 13.
• ISW assesses these infiltration attempts aimed to disrupt Ukrainian defenses ahead of renewed Russian offensives on the northern Sumy front on September 20 and 21, which ultimately failed to achieve significant gains.
• This tactic of using underground infrastructure for infiltration is not new; Russian forces have previously used gas pipelines and sewer systems to attempt surprise attacks in various locations including Avdiivka in 2024, Sudzha in 2025, and Kupyansk a year ago.
• Ukrainian troops have successfully countered these underground infiltration attempts by ambushing emerging forces and destroying pipeline routes, resulting in significant Russian casualties and disruption of their operations.