Ukraine

Why?

The campaign was a strategic Soviet success. For the first time, a major German offensive had been stopped before achieving a breakthrough, the maximum depth of the German advance was 8–12 kilometres (5.0–7.5 mi) in the north and 35 kilometres (22 mi) in the south. The Germans, despite using more technologically advanced armour than in previous years, were unable to break through the deep Soviet defences and were caught off guard by the significant operational reserves of the Red Army. This result changed the pattern of operations on the Eastern Front, with the Soviet Union gaining the operational initiative. The Soviet victory was costly, with the Red Army losing considerably more men and materiel than the German Army. The Soviet Union's larger industrial potential and pool of manpower allowed them to absorb and replace its losses. Guderian wrote:

With the failure of Zitadelle we have suffered a decisive defeat. The armoured formations, reformed and re-equipped with so much effort, had lost heavily in both men and equipment and would now be unemployable for a long time to come. It was problematical whether they could be rehabilitated in time to defend the Eastern Front ... Needless to say the [Soviets] exploited their victory to the full. There were to be no more periods of quiet on the Eastern Front. From now on, the enemy was in undisputed possession of the initiative.

https://en.m.wikipedia.org/wiki/Battle_of_Kursk

Now imagine the offensive being fought in this terrain is being fought by the Russians, but they can't protect their artillery enough to aggressively threaten with it (even worse Russia is running out of artillery pieces that work in the first place) and all of their mechanization, armor and veterans that knew how to blitz with them are blown up and dead.

This isn't an offensive, it is just marching the young of your country off to death. Yes, Russia is undeniably setting up the conditions for a decisive counter offensive. The best they can hope for is to tempt Ukraine into overcommitting too fast and sloppily in the counter offensive, which has admittedly worked very well in the past for Russia, but Ukrainian forces have decent combined arms capacity and training so that is a precarious hope for Russia to rely on.

Ukraine has the best most experienced UAV artillery spotters in the world hands down, and now they actually have the artillery to spot for. This will be the end result for Russians.

https://m.youtube.com/watch?v=bBM6gcQh_NU

It is a generally stated figure that most western m109 derived 155mm artillery systems can put a shell within 3m/10ft of a target under optimal conditions (ok so never optimal conditions in war but still these are very accurate tools). Notice that 3m is a joke compared to the effective anti-light/medium armor and infantry kill radius evident in this video. The fact that these shells are landing literally right on top of these targets is a cheeky flex and demonstrates how much more advanced these technologies are then they even need to be. These shells look like they were precisely dropped from a tower in range testing to film shell impacts... but no these were FIRED from a cannon aiming at that spot... and the gunners are still placing them RIGHT on top of tiny targets.

It is also observed that the high percentage errors in drift for short range firings is due to the comparison of small values resulting in high percentage errors. For example, for a short range firing with a muzzle velocity of 337m/s, the actual value of drift from FT 155-AM-02 for this case was 1.6 mils, whereas the IFDAP trajectory model calculated 1.69 mils. At a firing range of 2000 m, this difference is approximately only 0.18m, but 5.76 percent. Higher values of drift errors of up to 8 percent are also observed at the final 1000 m of the maximum range for each charge. However, for most real world applications, a firing charge that would barely reach the desired range would not be chosen because of higher variability in the behavior of the projectile. For typical values of ranges and muzzle velocities, represented by values corresponding to medium range, the drift errors are kept to within 4 percent.

https://apps.dtic.mil/sti/html/tr/AD1029824/index.html

....ok let us extrapolate into the medium term future, so the Russians are likely emplacing themselves as we speak in all the new territory they have gained.. and you can absolutely build a trench that will protect you from 155mm artillery fire.. but when the enemies 155mm artillery shells can be dialed in to ~3m or so now you are talking about them being able to send a 155mm artillery shell into that same trench you are hiding in that you spent so much time on digging out so 155m shells exploding nearby didn't hurt you. Do you reallyyy want to keep occupying that forward defensive position?

Against a weapon like that.. with thorough Ukrainian UAV spotting support over your head constantly... can your position even be considered defensive or emplaced or are you just a sitting duck?

A lot of western media will hyperfocus on advanced 155mm artillery shells like BONUS anti-heavy armor rounds, or worse hyperfocus on the necessity of GPS guided shells functioning in order for the artillery to be effective, but even a basic run-of-the-mill non-GPS guided HE 155mm shell is absolutely devastating and these systems like the Bohdana can place them with terrifying accuracy and consistency given the world ending power they create when they explode next to you.

The Russians can jam every damn GPS guided 155mm shell, go ahead sure, the old-ass WW2 vanilla style shells will still obliterate them all the same, the artillery will just have to move to a more advantageous position before it does where it can place fire more consistently. The difference to Russians is only that it means they have a little bit more time before they get blown up shrugs. Time to do what...?

...call in a localized counter attack with friendly armor to strike out and catch the enemy off guard in the process of sieging your position? Oh wait, I forgot, Russia didn't even have enough unarmored vehicles to get those soldiers to the front in an expedient manner in the first place, the idea of them launching an attack like that is a joke even if the armor on the vast majority of Russian armored vehicles could even remotely withstand 155mm artillery fire.

Yes foreign countries like North Korea and China can resupply Russia and make up for these holes, but the thing about high intensity armored warfare is that by definition it is not something a nation can simply endure while it accomplishes an objective, no, the very nature of the beast is that an armored counter offensive will devastate the Russian military and absolutely, unquestionably force them to begin responding to what Ukraine does not the other way around.

This is how war has always worked, since even before tanks and armor were invented.

None of this is new, what is new are two things, 1.) the way the media is consciously and subconsciously spinning this to give Russia's dominance an air of inveitability that is a mirage 2.) the ways in which Ukraine's UAV artillery spotters are innovating will be studied for decades.

Edit Yes of course the ~3m 155mm artillery accruacy figure I am citing is under optimal conditions, on the battlefield I am sure the effective accuracy with non-GPS guided shells at typical standoff ranges is much less, probably a multiple of that. However 1.) so are all of the enemy weapon systems being used back at Ukrainians by the Russians, in particular I think mathematically to keep up similar artillery fire rates as earlier in the war, Russia has to be using a smaller number of still working artillery much more unsustainably. This is a war deep into multiple dimensions of attrition on both sides but the enormity of this stark artillery reality for Russia is undeniable even from my far removed standpoint. It is a simple equation, how many guns are available to fire the necessary shells required, the less guns the more of a losing proposition it is. 2.) Just because most of the time you never move your 155mm artillery close to the front line for precision artillery fire because of the extreme risk doesn't mean you couldn't if you needed to during a highly organized offensive...