April 11, 2012. Professor Vali Nasr spoke about sectarianism and how it has emerged as a major fault-line in Middle East politics. Tensions between Shias and Sunnis have found new meaning in light of the Arab uprisings of the past year to define regional rivalries from the Levant to the Persian Gulf. The conflict in Syria, tensions in Bahrain, Lebanon and Yemen, simmering violence in Iraq and the larger regional rivalry between Iran and Saudi Arabia all tell of the growing importance of the sectarian divide.