When Russia began digging trenches in an area of Luhansk Oblast more than 30 kilometers behind the current line of engagement, it was easy to ridicule the strategy. And I did. The whole idea that Russia was building defensive positions so far from the action seemed to be an admission that it was going to cede much of the territory it had taken in Ukraine. The components of the works being assembled, like those unsecured “dragon’s teeth,” seemed laughable.

But what I derisively called the “Putin Line” was the beginning of extensive excavations and preparations across the occupied areas of Ukraine that saw Russian trenching machines excavate hundreds of kilometers of anti-tank and anti-personnel trenches. Trucks brought in pre-cast concrete pillboxes as cranes dropped off hundreds of thousands of those previously snicker-worthy dragon’s teeth. As the whole thing started to come together, Russia spread enormous numbers of mines in front of and among the other fortifications, creating minefields measured in kilometers and creating defensive lines that were anything but a joke.

It’s a massive, complex, interlocking system of defense and it’s effectively slowed Ukraine’s counteroffensive more than anyone—even Ukraine—expected. However, it wasn’t Vladimir Putin who designed the defenses. It was the former head of Russia’s operations in Ukraine, Gen. Sergei Surovikin. Surovikin has been missing in action since June after being sidelined in connection with the Wagner Group rebellion. Every day that his hands are off the controls, his creation becomes less of an obstacle and more of an artifact.