As well as security guarantees from NATO and the EU, a more concrete, iron air defense system in Ukraine will deter further attempts of Russian incursion in the future.
This analysis goes into how, why and more:
https://www.kyivpost.com/post/16478
Israel and many countries can do more to contribute to this joint defense system.
It will be similar maybe to the set up Israel has, so, they can at least advise on how to operate the tech of it.