Syrian rebels are holding hostage a convoy of United Nations peacekeepers in the Golan Heights, and have vowed to detain them until President Bashar Assad withdraws his forces from a Syrian village that has suffered heavy fighting. The U.N. on Wednesday confirmed that about 20 of its peacekeepers were being held by about 30 armed fighters in the Golan Heights, where the forces are charged with monitoring a cease-fire line between Syria and Israel. The capture, first announced in a rebel video posted on the Internet, was condemned by the U.N. Security Council, which demanded their immediate release. The U.N....