Yes, that is why it wasn't done, despite all cruelties against Ukrainians. One could argue, that as long as Russian troups are only engaged over Ukraine it is s

Yes, that is why it wasn't done, despite all cruelties against Ukrainians. One could argue, that as long as Russian troups are only engaged over Ukraine it is something different, but I think it is wise not to push this so far. But the other side is: if NATO wanted, they could have a no-fly zone over Ukraine any time.