Of course, the UN won't call it that, but that's what it is
This isn't like the no-fly zone over Iraq. We had just defeated Saddam, and the no-fly zone was a term of ceasefire. Nobody but the Libyan people are at war with the Libyan government. The UN has decided to take sides.
Unfortunately, the UN has a nasty habit of engaging in military conflicts without trying to win them. That habit has got to go, if the UN is to redeem its last few shreds of decency and usefulness. Libyans deserve better than a new tinhorn dictator to replace the old.