I agree with Mark Sumner in this article that a conclusion to this war where Russia is left with substantial forces and substantial Ukrainian territory is merely a temporary cease-fire rather than a permanent conclusion. Putin, via Russian demands in the peace talks, has made it very clear the Russians will happily accept a situation whereby Ukraine is left weakened and the Russians can try again a little down the road. Putin has shown no compunctions about breaking treaties, hence any conclusion to the current war that leaves Ukraine weaker and Russia stronger is not sustainable. If Ukraine wishes to permanently end this threat they must deal a crippling blow to Russia.
The first blow to Russia the Ukrainians are already on their way to achieving, which is the summary destruction of a large percentage of the Russian army. Ukraine can continue to achieve this but it will become more difficult as Russia concentrates its forces.
The second blow, is that Ukraine must take back Crimea and the separatist regions. Kos just wrote an excellent article on the more likely paths forward for Ukraine. Attacking Russia’s pincer coming through Izyum is a high priority. But then what? As Kos has amply argued previously the separatist regions have been building their own series of trenches and defensive installations mirroring those defending Ukraine now.
Looking at Donbas first, the two options are take the trenches head on, or go around. Taking them head on is not impossible, but highly likely to cost a large number of Ukrainian lives. It will require coordinated artillery, tanks, and infantry. Ideally they can achieve a breakthrough which then Ukraine could exploit by coming in behind the fortifications. A breakthrough is generally achieved by a concentration of forces which would be more vulnerable to enemy artillery. So the enemy artillery would somehow need to be neutralized first. Not impossible, but difficult and will require the West helping with all the equipment for counter-battery fire and also lots and lots of drones with enough range to reach the artillery. Some of the small drones being provided will not have that range (the drones will still be plenty useful, just not for taking out artillery 20 km away).
The other alternative is to simply go around the Donbas fortifications. But to do so, the easiest path will be through Russia. I know this sounds a little like Frodo being told to take the ring to Mordor. However, there is a distinct possibility that the Russians have not fortified their border as well as the separatists have. Both Russian overconfidence and corruption would lead them to neglect the possibility of a Ukrainian offensive into Russia. The way this would be run is as follows. The Ukrainians would retake Izyum as Kos has already suggested. They would then go on to take the area north of Severodonetsk back which is where most people would then expect them to turn south. Instead, they should continue to Millerovo inside Russia. This cuts a major N/S artery for Russian logistics. They drive south far enough to attack the separatists trenches from the flank greatly negating the value of trenches by coming in from the side.
Then comes an even bigger decision. Should this small foray into Russia succeed, taking Crimea can be made easier by the Ukrainians pushing south from Millerovo past Shakhty all the way to Rostov on Don. Then head west to cut off Crimea from the east. This sounds like horrendous logistics, but can be made easier if the forces in the separatist region can be eliminated. Then supply lines would go Shakhty then south without needing to go through Millerovo. The Ukrainians would be free to retreat from Millerovo having accomplished the plan.
Crimea would then be taken from two directions. From the north through Ukraine, but also from the east after going by Krasnador and Kerch. The Russian combat ships may no longer have a port to resupply at (other than Crimea) and hopefully NATO harpoons (or Ukrainian Neptunes) would pose enough danger to make them ineffective.
As an additional feint, at an appropriate time a thrust could be made from Karkiv towards Belgorod. Such a thrust would have two goals. First to get close enough to the city to destroy Rail lines and other critical infrastructure. Second, if done just before attacking Millerovo, it could pull critical Russian units out of position as the Russians react to an unexpected avenue to attack which even points towards Moscow. The goal would not be to take Belgorod. Approach the city, do as much damage to military infrastructure as you can, then pull out before the Russians could mount a significant counter-attack. Russian units might be redeployed from the south to help defend Belgorod and get caught stretched out on the move when the attack on Millerovo commences.
This plan is on the ambitious side and most would call it ludicrous. However, most people previously also considered Ukraine lasting more than a couple days against Russia ludicrous.
