15, citing miners.According to the Ukrainian miners, at some point, the shaft, located southeast of Pokrovsk, became too dangerous to work in due to constant Russian attacks. They switched to descending into the mine through another shaft.Pokrovsk, a crucial logistics hub for Ukrainian forces, has been the focus of fierce fighting as Russia intensifies its offensive in Donetsk Oblast.In the meantime, Russian troops advanced to within a mile of mine No. 3, raising fears that they could seize it and use its tunnels to outflank Ukraine's positions, according to the NYT.The miners and Ukrainian soldiers began drilling holes under the shaft to plant explosives, several workers told the outlet. The shaft was blown up around Dec. 20, 2024.Keeping the mine operational as long as possible was crucial to the Ukrainian economy, as it produced coking coal required for steelmaking — Ukraine's second-largest export after agriculture.An unnamed manager at Metinvest, Ukraine's largest steel producer, told the NYT that explosives were also planted in the facility’s two other shafts located further west, near the Ukraine-controlled villages of Kotlyne and Udachne.