On March 31, NATO formally warned the rebels to stop attacking civilians.Now, in fact the rebels had been attacking civilians even before they attracted US attention. Doesn't that mean that President Obama has a moral obligation to bomb the rebels? (Yes.)
Someone, I can't recall who, pointed out that despite the official rejection of "violent protest", the only protestors against the Arab dictatorships who've gotten US support have been the violent Libyan rebels. Nonviolent protestors have been on their own, and the US has stood complacently by while Bahrain imported foreign mercenaries to kill its own people. (How sad -- the Crown Prince of Bahrain will not be attending the Royal Wedding because of the unrest in his country, and perhaps coincidentally because "Human rights campaigners had petitioned against his attendance because of his government's treatment of protesters." There's so much hate in the world, isn't there?)