((a)) ** .—** The Secretary of Transportation shall arrange for the employment of the Department of Transportation’s vessels in steamship lines on such trade routes, exclusively serving the foreign trade of the United States, as the Secretary determines are essential for the development and maintenance of the commerce of the United States and the national defense. However, the Secretary shall first determine that those routes are not being adequately served by existing steamship lines privately owned and operated by citizens of the United States and documented under the laws of the United States.

((b)) ** .—** The Secretary shall have a policy of encouraging private operation of each essential steamship line now owned by the United States Government by—

((1)) selling the line to a citizen of the United States; or

((2)) demising the Secretary’s vessels on bareboat charter to citizens of the United States who agree to maintain the line in the manner provided in this chapter.