Ukrainians are fortifying and flooding underground pipes because Russian troops keep trying to crawl or walk in them

Source: Business Insider

Ukrainian troops have been defending the Oskil River, near Kupiansk for months. Kostiantyn Liberov/Libkos/Getty ImagesUkraine is dealing with its third known case of Russians using underground pipes to advance. A new report said that Russia used a gas pipe in Kupiansk to create supply lines close to the city.