((a)) ** .—** Under such regulations as the Secretary of Defense may prescribe, a sentence of confinement adjudged by a military commission under this chapter may be carried into execution by confinement—
((1)) in any place of confinement under the control of any of the armed forces; or
((2)) in any penal or correctional institution under the control of the United States or its allies, or which the United States may be allowed to use.
((b)) ** .—** Persons confined under subsection (a)(2) in a penal or correctional institution not under the control of an armed force are subject to the same discipline and treatment as persons confined or committed by the courts of the United States or of the State, District of Columbia, or place in which the institution is situated.