Russia didn't want it but needed to not have NATO on its doorstep a few minutes by missile from Moscow. The US public didn't want it. We already have an overloaded and mismanaged economy. The Ukraine public wanted it least of all - to be jobless, homeless, and looking for refuge in a country with a language they don't know.
Nor was it Pres. Putin, his own country already loves him and the US public already hates him. Nor Biden, he got some accolades for ending on war, he will soon lose them as this one drags on. That leaves... no. I can't say it. Maybe some President of a small country who gets to play with the big boys. No, it can't be.
there is a current war that does fit your description, how much trouble will i get if i side with yemeni freedom fighters vs the brutal ibn saud invaders?