Hagel says US commitment to Middle East security endures

* Pentagon chief says pledges backed by ships, warplanes, troops * First defense secretary at Manama Dialogue in five years * Visit comes amid Arab anger over U.S. policy in region (Adds Iranian question on Israel, edits) By David Alexander MANAMA, Dec 7 (Reuters) - Pentagon chief Chuck Hagel told Gulf Arab leaders on Saturday that the United States has a proven and enduring commitment to Middle ...