Why not? No-fly zones are typically imposed without troops on the ground. That’s one of the reasons for them to exist. I’m an American, and I have no trouble understanding what a no-fly zone is. I understand with clarity that it means an escalation of military involvement but that does not necessarily involve ground troops.

I don’t think you understand what a no-fly zone is.

It’s not wrong to fear a major world war scenario or be cautious of nuclear involvement, but using aircraft to stop Russia bombing civilians does not automatically equal nuclear engagement or all out war.