It’s true, if you look at the map, it would appear that Ukraine is winning because it’s recapturing its territory. However, this is partially the result of a strategy Russia has now abandoned. Russia initially believed that it could win the war within several days, and as a result put little effort into logistics or preparing its reserves.
Russia has learned from its mistakes. Its armed forces are abandoning their initial goal of seizing Ukraine’s capital, instead focusing their efforts on the south-eastern part of Ukraine. Furthermore, instead of rushing into battle, Russian forces now rely on heavy artillery to bombard Ukrainian positions for as long as needed before advancing to capture destroyed towns and villages. Thus, their casualty rates have decreased dramatically, while Ukrainian losses have increased.
Moreover, the Ukrainian army has already mobilized all of its reserves and is currently at maximum strength. Meanwhile Russia has been bloodied but retains the majority of its massive army. Russia is able to replenish their losses, whereas Ukraine cannot. This is why aid to Ukraine is a matter of urgency, before Russia can regroup and bring in more troops.
Artillery is the “bread and butter” of war. Ukraine’s “main” artillery calibers are 122 and 152 mm. The problem with 152 mm is that Ukraine DOES NOT produce ammo of this type (all it has is the legacy from the Soviet war machine). Thus, even though Ukraine has 152 mm cannons, it is quickly running out of ammo. Given the intensity of the conflict, it won’t be long before Ukraine doesn’t have any 152 mm ammo left. If that happens, Ukrainian forces won’t be able to shoot back, and Russian artillery will overwhelm them.
Ukraine would also greatly benefit from NATO’s modern 155 mm artillery, such as the M109 Howitzer. Both 152 mm and 155 mm are considered “heavy artillery” and are the main damage dealers on the battlefield.
The same goes for Multiple Rocket Launch Systems (MLRS for short). Ukraine uses old soviet MLRSs like Grad, Smerch and Tornado, and is currently lacking both MRLS units and ammo.
Artillery will play a major role in breaking through Russian lines by enabling Ukraine to strike critical military facilities such as command centers, ammo storage, and fuel depots. Additionally now that Russian troops are focusing on fortifying seized territory, more artillery will be necessary to dislodge them.
Tanks are the “iron fist” of any push. Ukraine is lacking heavy armor - both Tanks and APCs.
Any assault on heavily defended areas without tanks and APCs is a suicide. Precisely for that reason, Ukraine is not able to launch an attack towards Mariupol in the southeastern part of Ukraine, despite it being under siege for over a month now. Ukraine desperately needs hundreds of tanks and APCs to deal a serious blow to the russian forces that will drive them away for good!
In essence, a successful attack against a well-armed enemy (which Russian forces are) requires a “full house” approach - air attack, followed by an artillery barrage, followed by an armored fist strike (tanks and APCs). Sure, you can deal the blow with JUST tanks, but half of them will be destroyed by the time you reach the enemy positions. Only when you have a complete mix of “ingredients” you can expect a good result.
Su-24 is an “all-weather attack aircraft”. It is used as a “first strike” weapon on well-defended positions and plays a crucial role in breaking the defensive line.
Russia’s air force is enormous, over ten times as large as Ukrainian air force. Without sufficient anti-aircraft systems, Russia will have free reign to destroy everything - artillery, command posts, tanks and entire Ukrainian cities. That is precisely why at the beginning of the invasion Russia was trying hard to achieve air dominance. If they succeed, it will just be a matter of time until Russia wins the war.
Moreover, anti-aircraft systems are responsible for protecting Ukraine from cruise missiles, which Russia has in huge quantities and has been using with complete disregard for civilians.
Eastern European countries like Romania, Bulgaria, Slovakia, Poland, and the Czech Republic have most of the weapon systems listed above. Moreover, many of the aforementioned countries have openly stated that they are willing to provide these weapons, as long as NATO or USA will resupply them with newer ones (rightly so - if war breaks out on their territory they must have weapons to defend themselves).
Actually, yes. Soviet weapons are simple, Western weapons are more advanced. The closest analogy would be trading an old pick-up truck for an expensive modern sedan. Would you be able to use it? Sure. It may feel a bit weird at first, but in essence “driving is still driving”. It’s similar to Western weapon systems. It will take some practice to get used to, sure - but tanks are tanks essentially - “aim and shoot”. The Ukrainian army WILL be able to use western weapon systems. This is just a matter of time.