U.N. Secretary-General Ban Ki-moon addresses a summit of the Alliance of Civilizations, a forum promoting understanding between the Western and Islamic worlds, in Istanbul, Turkey, Thursday, May 31, 2012. Ban called on Syria Thursday to stop its attacks, saying U.N. observers monitoring the cease-fire were not there to watch the killing of innocent people, days after more than 100 people were massacred in Syria's central Houla region.(AP Photo)