The Ukrainians have to win.
To win, Ukrainians will have to kill 5 Russians for every Ukranian killed. Russia’s biggest asset is their huge supply of expendable soldiers/citizens/conscripts.
Even at that rate it will take years. Unless they can kick Russia out of Crimea and the East real quick, how can they “win”?
Well, it's a little bit less than this ratio. Common military reports state that it takes about 5 offenders vs every 1 defender to take a well defended area. The Russians don't have this many troops. Yes, they are importing Syrians and Nazi merks (like Wagner). But they will run out of troops eventually. I don't believe that Ukraine will be able to take Crimea. But (and this is a tragedy for Ukraine); Ukrainians win by just surviving. It's going to be a battle of the wills. But here's the difference, the Russians can just go home when they lose their will. The Ukrainians are fighting in their home. They have no choice. Ukrainians win by persevering their state.
On the other hand, the Russians already lost. They attacked in order to split Nato in half and convince the other eastern European countries to turn towards Russia. That's been an absolute failure.
Note that Russia is the "defender" already for a large part of the Eastern and Southern parts of the country, so the 5-to-1 calculus there is against Ukraine. I read somewhere that Russia is also conscripting residents of the "people's republics" to do the upkeep and policing of the occupied territory, which frees actual soldiers to fight the Ukrainian army.
The big fight is due for the next couple of weeks, when Russia tries to push south from Izyum and cut off Ukrainian defenders deeper in Donbas. I have no idea how that will turn out, but I'm not optimistic. Russian troops may be less motivated and some of their equipment broken, but the initial numbers advantage is too great. And Russia has much more long range striking capability. Recently Russia said that they had destroyed S-300 anti-air system in Mykolaiv; if true, that means Ukrainian air defenses are going down. Which means more missiles and planes will hit their targets.
Jay: I don't disagree with you. I'm very pessimistic about this war. Russians hold most of the short term cards. We mostly send defensive weapons to Ukraine that have short range. The Russians will just use their long term artillery and aircraft and just pound the Ukranians. And starve them to death. But the west should do everything in our power to bankrupt Russia. And be ready to prop up whatever remains of Ukraine with massive western support and aid. I don't think that Russia will take western Ukraine at least. But the Russians have chosen war. And we need to find a way to stop them at some point.
There are limits to what US and NATO can do.
Providing state-of-the-art western weapons systems isn't just about money (although it is about that too), because the Ukrainian army would need to be trained to use them. The better option of sending old soviet weapons is good, but not limitless: the other countries are not going to just de-arm their own armies, and even if US promises to give them replacements, that takes time. So does producing new weapons off the assembly line.
Many EU/NATO countries haven't really stocked up on weapons since the end of the cold war, and just have enough for their own active duty soldiers.
If Russia manages to break through the defenses south of Izyum, the war could become very long. if it fails, maybe Putin would be willing to cut some sort of ceasefire or a peace deal at least. After that, I hope that US and EU realize that they can't just drop the financial support. We need to have a Marshall-plan like rebuilding package for Ukraine, including reforms to curb the corruption and enforce public institutions, or that Money's just going to be pocketed by the Oligarchs and corrupt government officials like in Afghanistan. Ukraine was one of the most corrupt countries in Europe before the war. The good thing is that some of Putin's confiscated war chest might be used to finance this plan, but just throwing money at a problem hasn't proven to be very reliable means of nation building.