An undercover Israeli policeman dressed as a Palestinian woman opens a car door after detaining a Palestinian protester during clashes in Shuafat refugee camp, in the West Bank near Jerusalem May 15, 2011. Israeli security forces had been on alert for violence on Sunday, the day Palestinians mourn the "Nakba", or catastrophe, of Israel's founding in a 1948 war, when hundreds of thousands of their brethren fled or were forced to leave their homes. REUTERS/Baz Ratner (WEST BANK - Tags: POLITICS CIVIL UNREST ANNIVERSARY)