katherine herridge has been with this since day wn one. >> reporter: there are no matches for americans in the data bases or watch list. a complicating factor for investigators is that one of the names is so generic, it's described as the somali equivalent to john smith. the mall itse selself is a depa from of the places. because a terrorist group has never tweeted out names in the past. the ranking member of the house foreign affairs committee telling fox news that the attack appears to be retaliation for the kenyan government's recent deployment of troops to small la where al shabaab wants to establish an islamic state. >> they are particularly annoyed at the kenyan government because they've been cooperating with