Ukraine’s Offensive Runs Into Russian Defensive Wall – Ex-Estonian Spy Chief

"The defensive lines the spymaster was referring to are also known as the ‘Surovikin Line’, informally named after General Sergei Surovikin, the Russian commander tasked with commanding the Joint Group of Forces in the Special Military Operation Zone between October 2022 and January 2023....Ukraine’s NATO-armed and trained military has lost thousands of troops and hundreds of
heavy tanks and armored vehicles since kicking off its so-called counteroffensive on June 4. 

"The bulk of the fighting is taking place on the southern front,” Sachs said in an interview with Estonian television.....“The Ukrainians are yet to push deeply into Russian defensive lines. The Russians have built long defensive lines along the entire length of the front, with the fewest defensive positions in the north. Russia considers it very important to hold onto the southern part of the front, so more defensive lines have been built there. Ukraine attempted to break through the Russian defensive line in three places, but not using very energetic maneuverable units, but rather carefully with artillery fire. So I wouldn’t expect very fast or deep progress from such attacks,” Sachs said." Sputnik