Mr. Obama has told his staff to study previous uprisings in Eastern Europe, the Middle East and Southeast Asia for lessons about how they unfolded and what role the United States played. He won’t lack for impassioned advice: Among his staff members is Samantha Power, a human-rights expert who won a Pulitzer Prize for a book chronicling American foreign-policy responses to genocide.

Former officials are also taking up the call. Anne-Marie Slaughter, who recently resigned as the State Department’s director of policy planning, said in a tweet: “The international community cannot stand by and watch the massacre of Libyan protesters. In Rwanda we watched. In Kosovo we acted.”…

The question is also complicated by the way Libya appears to be splintering: along tribal lines, with the historically rebellious east falling quickly to the rebels while western Libya, traditionally more loyal to Colonel Qaddafi, remains under his control. While none of this argues for keeping the colonel in power, it does suggest the challenges the United States would face in trying to mediate between groups after he is gone.