((a)) When a treaty is in effect between the United States and a foreign country providing for the transfer of convicted offenders, the Secretary concerned may, with the concurrence of the Attorney General, transfer to such foreign country any offender against chapter 47 of this title. Such transfer shall be effected subject to the terms of such treaty and chapter 306 of title 18.

((b)) Whenever the United States is party to an agreement on the status of forces under which the United States may request that it take custody of a prisoner belonging to its armed forces who is confined by order of a foreign court, the Secretary concerned may provide for the carrying out of the terms of such confinement in a military correctional facility of his department or in any penal or correctional institution under the control of the United States or which the United States may be allowed to use. Except as otherwise specified in such agreement, such person shall be treated as if he were an offender against chapter 47 of this title.