Geolocated footage shared on Sept. 21 and analyzed by the Institute for the Study of War indicated that Ukrainian armored vehicles advanced south of the anti-tank ditches breaching the Russian tri-layered defense, and engaging in limited combat just west of  Verbove on the southern Zaporizhzhia front.

The institute said it is unclear if Ukrainian forces retain these positions. However, this is the first observed instance of Ukrainian forces operating armored vehicles beyond the Russian tri-layer defense.

"The presence of Ukrainian armored vehicles beyond the final line of the current Russian defensive layer indicates that the Ukrainians have secured their breach of the first two lines of this layer sufficiently to operate vehicles through the breach," the ISW said.

Ukrainian forces have likely suppressed Russian artillery and other anti-tank systems in the area enough to bring their vehicles forward, the experts added.

"The Ukrainian ability to bring armored vehicles to and through the most formidable Russian defenses intended to stop them and to operate these vehicles near prepared Russian defensive positions are important signs of progress in the Ukrainian counteroffensive," the ISW concluded.

Ukraine war latest: Russia launches mass missile attack on energy infrastructure; Ukraine reportedly hits airbase in Crimea

Key developments on Sept. 21: * Russia launches first mass missile attack on energy infrastructure in six months * Ukraine reportedly strikes Russian air base in Crimea * Kyiv receives military aid from Germany, Sweden, funding from U.S. * U.K. Defense Ministry: Lack of rotations likely one of…

The Kyiv IndependentAlexander Khrebet