; (2) by redesignating paragraphs (2) through (4) as paragraphs (3) through (5), respectively; (3) by inserting after paragraph (1) the following: (2) on vessels contracted by the United States Government, subject to subsection (b); ; and (4) by adding at the end the following: (b) Subsection (a)(2) shall only apply to vessels that are contracted by the United States Government and that carry more than 75,000 Metric tons of food aid per year in accordance with section 55305 of title 46, United States Code. . 10. GAO report on national maritime strategy The Comptroller General of the United States shall complete a study and submit to the Committee on Commerce, Science, and Transportation of the Senate, the Committee on Armed Services of the House of Representatives, and the Committee on Transportation and Infrastructure of the House of Representatives, a report on— (1) the key challenges, if any, to ensuring that the United States marine transportation system and merchant marine are sufficient to support United States economic and defense needs, as articulated by the Maritime Administration, the Committee on the Marine Transportation System, and other stakeholders; (2) the extent to which a national maritime strategy incorporates desirable characteristics of successful national strategies as identified by the Comptroller General, and any key obstacles (as identified by stakeholders) to successfully implementing such strategies