> Ukraine is never going to recapture the territory that it has lost without European troops on the ground.

This is such a defeatist attitude. By that logic North Vietnam would never have recovered South Vietnam.

A lot of things can happen if you just refuse to be defeated. Hannibal killed almost the entire Roman army at Cannae, but the war ended 15 years later with full victory by the Romans.

In 1940, Britain was the only country in Europe fighting Germany. Many had fallen, were neutral or were fighting with the Nazis (Russia, Italy, etc). But in the end Britain won.