The Dnipro River protects Ukraine in the South. But Kyiv is vulnerable if the Russians break through defensive fortifications in the east.
Russia claims it only wants Crimea, Donetsk, and Luhansk.
Not sure anyone believes that but it would be a logical basis for a peace deal.
You wrote something similar to me in regard to Odessa - as if a river is some mystical, inpenetrable barrier that can't be overcome.
Armies (and Navies and Air Forces) have breached/crossed rivers for thousands of years. This one has.
Not sure what ypu're thinking.