FILE - In this Jan. 28, 2011 file photo, anti-government activists clash with riot police in Cairo, Egypt, to challenge President Hosni Mubarak's 30-year rule. Ten years ago, an uprising in Tunisia opened the way for a wave of popular revolts against authoritarian rulers across the Middle East known as the Arab Spring. For a brief window as leaders fell, it seemed the move toward greater democracy was irreversible. Instead, the region saw its most destructive decade of the modern era. (AP Photo/Ben Curtis)