Unwinnable regarding Crimea peninsula and probably the separatist areas. Because Russia is not going to let go of Crimea, they’re just not. There’s nothing they won’t do to keep it.
That is probably true. War isn't a board game in that winning only generally happens when your opponent can no longer continue fighting. Some people think that once one side achieves certain objectives the war is magically over. Once Russia started the war, UA gets a vote too.
Likewise, the win conditions for UA are when Russia decides it needs to negotiate because it can't really continue and the options for UA are not likely to improve if they don't reach some sort of agreement at that point.
Just like war is politics, victory is consensus that going forward is unlikely to yield much better results.
When you say winning is impossible the question is what winning conditions are and to what degree. So, I don't see how we can say winning is impossible for either side until we understand what winning means to either side. Most of the time winning the best possible outcome given the circumstances and the circumstances are still dynamic. UA lost ground and took high casualties in the Donetsk pocket recently but gained ground in the Karkiv and Kerson fronts. They knocked out upwards of 40 ammo dumps, Command centers, large barracks and other high value targets in just the last week alone. They have been conducting a building offensive near Kerson that is still ramping up. So, they are not out of the fight at this point.
