(b)
Notwithstanding any other provision of law, the Secretary of Defense with respect to civilian employees of the Department of Defense other than employees of a military department, and the Secretary of each military department with respect to civilian employees of such military department, may, under such regulations as each such Secretary may prescribe with respect to the employees concerned and in accordance with the policy and other provisions of this section, establish and operate programs of rotation which provide for the granting of the right to return to a position in the United States to each civilian employee in the department concerned—
(1)
who, while serving under a career-conditional or career appointment in the competitive civil service, is assigned at the request of the department concerned to duty outside the United States,
(2)
who satisfactorily completes such duty, and
(3)
who applies, not later than 30 days after his completion of such duty, for the right to return to a position in the United States as provided by subsection (c).
The Secretary of the department concerned may provide by regulation for the waiver of the provisions of paragraphs (2) and (3), or of either of such paragraphs, in those cases in which the application of such paragraphs, or either of them, would be against equity and good conscience or against the public interest.