"It is true that those who worked in or on the Arab countries were well aware of the pent up popular frustrations and the poor records of the regimes that claimed to govern them. Yet, these same regimes had been in power for 40 years or more, largely following the same policies and practices. They trumpeted 'security and stability' as their virtues. Challenges to their rule had been few and far between, not to mention short lived. You see, these regimes had become quite adept at coup-proofing themselves. They created overlapping and redundant security and intelligence services, all competing with one another, and each one reporting to the leader or his most trusted family members. [...] Thus, since the 1970s, few threats existed to the entrenched regimes and almost none came from within the ranks of militaries or security/intelligence services. Nevertheless, there is almost nothing the autocratic Middle East regimes feared more than large, widespread, and prolonged demonstrations and rioting. Knowing that their police forces might not be able to restore order, they would then face the dreaded need to call upon army units to confront their fellow nationals."
Marine Corps University: http://www.mcu.usmc.mil/
MES [Middle East Studies] Insights (January 2014), v.5 no.1