On a hot moonless night two weeks ago, elite U.S. Army Rangers aboard helicopters slithered down ropes onto a roof in northern Mogadishu to arrest 39 Somalis. Under intense questioning, one man in custody confessed he was General Mohammed Farrah Aidid, the warlord whose fighters have been attacking peacekeeping troops since June. But the big catch quickly turned into an embarrassing fumble. Though he bore a slight resemblance, the arrested man was not Aidid. He turned out to be a former police chief who assumed the fake identity out of fear that the soldiers would shoot him.
Like the 1982 U.S....