“Cutting off water to an invader is a sovereign right. If the Russians want water they can go back to Russia. Or Hell. Whatever.”
Historically, yes. But we are in the 21st century now, and it could be considered a crime against humanity. One can only survive about three or four days without fresh water. And dying of thirst is brutal.
Here is some info on the matter:
https://casebook.icrc.org/case-study/water-and-armed-conflicts
“Could be”...by Russia and no one else.
Do you think that Crimea was completely uninhabited until the canal was completed in 1975? Even today, 80% of the water from that canal goes to agriculture. Nobody’s going to be dying of thirst in Sevastopol three days after Kherson is liberated.