The National Guard Bureau chief told lawmakers today there are 782 Guard members serving at the United States-Mexico border, while the secretary of defense has authorized up to 4,000 troops to be deployed through Sept. 30. The source of funding and length of their mission are yet to be determined, according to Air Force Gen. Joseph Lengyel. Testifying before the House Appropriations defense subcommittee, Lengyel said, "The border security mission effectively is a national security issue, and the secretary of...