The UN Resolution in March 2011 only authorised the implementation of a no-fly zone over Libya. That objective was achieved almost immediately thereafter, but all along, the intent of the US and European leaders was to effect regime change. They are now closer to that objective - though the only thing they were authorized to do by the UN was to implement a no-fly zone. By openly supporting and arming the rebels, they have thrown caution to the winds, and are on the threshold of regime change, but no one knows what the new Government of Libya will be like, who will head it, and so on. A typical case like Iraq and Afghanistan - they have a plan for the war, but not for the peace that follows.
Worse, there are now reports that the supposed scent-of-victory situation in Tripoli is mere war propaganda, and that Gadhafi' son and heir apparent has not really been captured. He appeared in person before international reporters in a hotel in downtown Tripoli. This is egg on the face of not just the rebels but all who are supporting them.