"I think there were very, very unrealistic expectations in Washington, including in some parts of the administration, that the Arab Spring was going to push out these authoritarian regimes and democracy is going to flourish because that's what people want," he said on CNN's Axe Files podcast on Monday.
Brennan also noted that, although the decision to withdraw US troops from Iraq in 2011 was unlikely to have been the cause for the sectarian violence in the country, it was likely "a contributing factor" to the formation and strengthening of Daesh, outlawed in Russia, the United States and other countries.
A wave of Arab Spring uprisings spread from Tunisia to Egypt, Bahrain, Libya, and elsewhere across the Middle East in 2011. The fall of a number of authoritarian regimes has led to increased instability in the region.
