Very near to where the current fighting is taking place, in 1944 the Russians pushed a bulge into the German lines inviting the Germans to pinch it off and obliterate the Russian army in that area.
The Russians knew what was about to happen and built similar defensive lines to what they have today in Ukraine, in the largest armored battle in world history the Battle of Kursk began and ultimately ended the ability of the Germans to take the offensive on the Eastern Front.
It is interesting how we’ve gone from the Ukrainian army being caught in a “cauldron” from a Russian offensive to exactly the same thing from a Russian defensive posture. Hilarious, really.
The reality is the Russian military is fake and Potemkin. Some of its best leaders have been bombed out the Russian sky by Putin. Only intentionally limited aid by the Biden admin & EU has saved the Russian army from total defeat at the hands of Ukrainian citizen soldiers.