Figuring out who is responsible for the attack on the Cole promises to be a difficult process. Counterterrorism officials in Washington say they will divide their likely targets into three categories. The first key group will be indigenous Yemeni factions that are known for occasional lawlessness but are difficult to track.
Most notable among these is the Aden-Abyan Islamic Army, an extremist organization once led by Zein Al-Abideen al-Mehdar, a.k.a. Abu Hassan, who was sentenced to death for kidnapping 16 Western tourists and executed on Oct. 17, 1999.
The Aden-Abyan Islamic Army is not on the State Department's list of terrorist...