Ukraine cannot win here. Russia has the world's most devious and cruel combat engineers laying in miles and miles of entrenched defence fortifications. Backed by Russia's world leading artillery battalions, there is no way Ukraine can push back Russia without battlefield nukes.
Russia is already laying in massive quantities of entrenched long range radar, antiaircraft batteries and missiles. US cannot acquire air power over that region any longer. If you have played a realistic war flightsim like Falcon 5.0, you will know air power cannot prevail against Russia's AA tech.
The F-35 has been operating over Syria for years against those supposedly infallible Russian AA defenses. So far the only thing that's been able to hit them is a bird.