In exchange for Jordan's return of the captured Mossad assassins, Israel released Hamas' spiritual leader, Sheik Ahmed Yessin , who had been imprisoned in Israel since 1989.
Jordan did not hold any Mossad assassins.  
mnli hypothesis: Jordan did not hold any Mossad assassins.   premise: In exchange for Jordan's return of the captured Mossad assassins, Israel released Hamas' spiritual leader, Sheik Ahmed Yessin , who had been imprisoned in Israel since 1989.