Turkey returned fire after Syrian mortar bombs landed in a field in southern Turkey on Saturday, the day after Prime Minister Tayyip Erdogan warned Syria that Turkey would not shy away from war if provoked. It was the fourth day of Turkish retaliation for firing by Syrian forces that killed five Turkish civilians on Wednesday. Turkey has nearly 100,000 Syrian refugees in camps on its territory, has allowed rebel leaders sanctuary and has led calls for Assad to quit. Its armed forces are far larger than Syria's.