It was the imminent threat to civilians in Libya's second city, Benghazi, that clinched the argument at the UN for outside intervention. But with multiplying reports that the fight is on for Syria's second city, Aleppo, the signs are that even government air strikes will not spur a similar Western and Arab alliance into action. Morally, that has to be deplored. The parallels between the plights of the two populations are clear. But these are different times, and Syria is not Libya.