A Soufan Group IntelBrief 'The Wider Threat of Terrorist Prison Breaks' which opens with a reminder:
Breaking their members out of prisons is one of the most effective tactics used by terrorist groups to reenergize and repopulate their ranks
Link:http://soufangroup.com/tsg-intelbrie...prison-breaks/

Since the Yemen is one of the cited examples, I do wonder why no jails have been opened on its islands, in particular Socotra. Somehow I doubt yemeni jails match those in the visiting facilities in the West.