Actually not true. Many Ukrainian fighter pilots have received training in the US, where they flew F-16:s. (That is, before the current phase of the conflict.)
The hard part is actually the maintenance crews. A modern fighter plane requires constant intensive mainentance, they generally spend much more time being worked on than they spend actually in the air. And this maintenance work requires a lot of specific skills that don't necessarily translate well or at all between aircraft types.
The hard part is actually the maintenance crews. A modern fighter plane requires constant intensive mainentance, they generally spend much more time being worked on than they spend actually in the air. And this maintenance work requires a lot of specific skills that don't necessarily translate well or at all between aircraft types.