An undercover Israeli police officer holds a weapon as others detain a Palestinian suspected of throwing stones during clashes in the East Jerusalem neighbourhood of Wadi al-Joz March 16, 2010. Palestinians mounted violent protests in a "day of rage" in Jerusalem on Tuesday and a U.S.-Israeli crisis over a Jewish settlement project deepened with the cancellation of a U.S. peace envoy's visit. REUTERS/Baz Ratner (JERUSALEM - Tags: POLITICS CIVIL UNREST IMAGES OF THE DAY)