Marty, I can't speak in the name of Jens Stoltenberg, the Secretary General of NATO. This is the position that NATO took and decided to communicate. I won't go into the different hypotheses for why it did so.
I can tell you, though, that many members of the alliance want to make sure that we do as much as possible without crossing this red line posed by NATO. We know that the question of the airspace in this conflict is important. That is why we've provided ammunition and lethal aid, and that's why other countries have also done so in a very substantial manner.