NATIONAL HARBOR, MD -- U.S. commercial shipping leaders, meeting Wednesday on the closing day of the Sea-Air-Space conference, voiced concern about ensuring strategic sealift capabilities to counter possible military aggression. A military sealift operation would rely on commercial vessels to help move supplies, assets and forces. China operates one of the world's largest merchant fleets with more than 5,500 vessels, yet the United States has just 85 flagged commercial ships active in trade internationally. The shipping leaders spoke about safeguards...