Julian Borger looks at the logistics of setting up the UN-approved no-fly zone:
If this had been a Bush-era 'coalition of the willing' operation, it could have been put into action quite rapidly. The US would have done all the fighting with a few token British and French planes along for company. But the Obama administration, which tried very hard to avoid this moment, is insistent that the Arabs and Europeans must at least be seen to take the lead, and that will take more time. There is a trade-off between speed and making it look right.
... The time pressure is intense. If Benghazi falls before the air operation gets off the ground, it would be the worst of all worlds. Gaddafi will have defied the UN, and any subsequent air strikes against his forces could simply worsen the reprisals against the rebels and the people of Benghazi.