"Islamist violence and regime stability in Saudi Arabia"

Thomas Hegghammer (pdf.) here via AbuMuqawama

The question now is whether future Saudi returnees from Iraq pose a security risk similar to that posed by the returnees from Afghanistan in 2002.56 The ‘Saudi Iraqis’ will be at least as
battle-hardened as the ‘Saudi Afghans’, given the higher level of military activity and the more extreme tactics used by militants in Iraq. Returnees from Iraq will undoubtedly represent a considerable threat and may well succeed in carrying out major ad hoc operations.