 Ukraine reaches Russia's last defence line in Zaporizhia Oblast. The Institute for the Study of War ISW has reported that Ukrainian armoured vehicles are already operating beyond the last line of Russian defence fortifications, which Ukrainian forces are currently breaking through in the west of Zaporizhia Oblast, although it is too early to claim that Ukraine's armed forces have completely broken through this Russian defence layer. Geolocated footage posted on September 21 indicates that Ukrainian armoured vehicles advanced south of the Russian anti-tank ditches and dragon's teeth obstacles that are part of a tri-layered defence and engaged in limited combat immediately west of Verbov. It is unclear if Ukrainian forces retained these positions. However, the ISW said. The ISW reported that they saw for the first time that Ukrainian forces are using armoured vehicles outside of Russia's three-layer defence. The ISW emphasises that the presence of Ukrainian armoured vehicles beyond the last line of the current Russian defence layer indicates that the Ukrainians have sufficiently breached the first two lines of this layer to move their vehicles forward. The Ukrainian ability to bring armoured vehicles to and through the most formidable Russian defences intended to stop them and to operate these vehicles near prepared Russian defence positions are important signs of progress in the Ukrainian counter-offensive. The ISW noted. The ISW noted that Ukrainian forces have also advanced to the west and southwest of the settlement of Verbov. Thus, the Russian troops currently defending in the western part of Zaporizia Oblast didn't have an ability to prevent the Ukrainian troops from advancing gradually but confidently since mid-August. The ISW wrote that it constantly observes the slow but regular advance of Ukrainian troops in this area despite the fact that the Russian military is transferring parts of relatively elite units here to strengthen its defensive operations.