In response to the Ukrainian counteroffensive in June 2023, the Russian Army significantly expanded their minefields, quadrupling their depth and increasing mine density. This move stalled Ukrainian advances, given their standard mineclearing equipment’s inability to handle these expanded fields. However, this rapid expansion has depleted Russian minelaying resources, resulting in uneven minefields and potential opportunities for Ukrainian forces.
  

Key Points: 

1. The Russian Army expanded the depth of their defensive minefields from 120 meters to 500 meters and increased the density of mines within them, severely slowing the Ukrainian counteroffensive.
2. The Ukrainian UR-77 explosive line-charge can typically clear lanes around 100 meters long, making it challenging to navigate these broader minefields.
3. Despite the initial hindrance, Ukrainian brigades advanced approximately 10 miles in Zaporizhzhia and Donetsk, recently liberating Robotyne, a significant Russian strongpoint.
4. The rapid minefield expansion has strained Russian resources, resulting in uneven and potentially more navigable sections for Ukrainian forces.
5. Analysis from the Royal United Services Institute highlighted that the Russians learned from previous skirmishes, realizing that expanded minefields can effectively slow down Ukrainian assaults.

Source: https://www.forbes.com/sites/davidaxe/2023/09/05/to-slow-the-ukrainian-counteroffensive-the-russian-army-quadrupled-the-size-of-its-minefields/