On Jan. 26, Egypt banned protests and tightened security following riots against the regime of President Hosni Mubarak. The U.S. called on Cairo to show restraint and allow the demonstrations. Tunisia's leadership was recently toppled by a popular uprising. Mubarak, too, may be vulnerable. He is 82 and has no clear successor. Unemployment in Egypt is running at 9 percent despite 5.3 percent economic growth last year.