We all know what this means in practice — there are no UN aircraft carriers, needless to say — but you know how the imprimatur of international legitimacy brightens Obama’s day. And the request for help isn’t as unlikely as it would have seemed just a week ago. Read this NYT assessment of the stalemate in and around Tripoli. Qaddafi isn’t strong enough to recapture nearby cities, but the rebels aren’t strong enough to break his hold on the capital, which appears to have quieted down. If he keeps resupplying via air, at the very least he can hold on in his corner of the country for a good long while. At worst, he can build up to the point where he’s steamrolling people again.

It’s 3 a.m. and the phone is ringing.

By invoking the United Nations, the council, made up lawyers, academics, judges and other prominent figures, is seeking to draw a distinction between the airstrikes and foreign intervention, which the rebels say they emphatically oppose.

“He destroyed the army. We have two or three planes,” said Abdel-Hafidh Ghoga, the council’s spokesman, speaking of the rebels’ military disadvantage. He refused to comment on the council’s deliberations or any imminent announcement, but said: “If it is with the United Nations, it is not a foreign intervention.”…

There was no indication that the United Nations Security Council members would approve such a request, or that Libyans seeking to topple Colonel Qaddafi would welcome it. Russia has dismissed talk of a no-fly zone to curb Colonel Qaddafi’s still-active air force, and China has traditionally voted against foreign intervention.

Even so, the discussions signaled a rebel movement both impatient with a military stalemate that has crippled the country, and out of good options.

The worry, supposedly, is that Qaddafi will demagogue the airstrikes as evidence that the protests are a foreign plot. Really? Who, exactly, is still undecided on the uprising and waiting to hear from Qaddafi before determining how they feel about it? Wouldn’t a televised statement on Al Jazeera from the rebel leadership in Benghazi be proof enough that the intervention was requested, not imposed?

If the White House wants to worry about something, they should worry that imposing a no-fly zone would be …. not so easy:

If a no-fly zone is implemented, one of the biggest worries for U.S. planners will be Libya’s surface-to-air missile batteries along its coastline, especially its so-called SA-6 missiles, which, though designed years ago by the Soviet Union, remain able to shoot down U.S. and European fighters, several analysts said.

Libya is believed to have about 50 SA-6 missiles, which are easy to move to avoid detection. Pentagon planners probably would seek to neutralize the SA-6s by warning Libya’s military not to target NATO aircraft but also with airstrikes against batteries that took threatening actions, such as activating their radar, the officers said…

To carry out patrols over Libyan airspace 24 hours a day, the U.S and its allies would need hundreds of aircraft, including fighters and refueling tankers, Dunn said. The U.S. could reduce the number of aircraft required by flying only during the day, when attacks on anti-government rebels are most likely, or by going after only Libyan airplanes, not helicopters, he said.

On the other hand, Danger Room notes that Libya’s surface-to-air batteries didn’t perform so well against the U.S. 25 years ago and, er, that they haven’t been upgraded since. (It’s also unclear how many batteries still function at all and how many are in rebel hands.) Nonetheless, the Pentagon seems unenthused about a new military operation, likely because of the logistics involved rather than the threat to U.S. airmen, and as J.E. Dyer pointed out earlier, U.S. officials are privately conceding that talk of a no-fly zone is an empty threat — for now. What happens, though, if the rebel leaders call the west’s bluff by formally requesting one, for the express humanitarian reason that they fear a massacre if Qaddafi hangs on much longer? There’s no way Obama, Cameron, Sarkozy et al. will say no and risk the public backlash if Qaddafi ends up using chemical weapons. If the request comes, it’ll be honored. I think.

The alternative, of course, is to stay out and start arming the rebels instead, but if even a hawk like Lindsey Graham is leery of that, you can imagine what the White House is thinking. Exit quotation from Hillary, who’s cool to the idea of leaving any U.S. fingerprints on any intervention: “You see a constant drumbeat [on Middle Eastern websites] that ‘the United States is going to invade Libya to take over the oil and we can’t let that happen.’ And we are not going to do that.”