(1)
The Secretary of Defense shall prescribe in regulations—
(A)
a requirement that a program manager and a deputy program manager (except as provided in paragraph (3)) of a major defense acquisition program be assigned to the position at least until completion of the major milestone that occurs closest in time to the date on which the person has served in the position for four years; and
(B)
a requirement that, to the maximum extent practicable, a program manager who is the replacement for a reassigned program manager arrive at the assignment location before the reassigned program manager leaves.
Except as provided in subsection (d), the Secretary concerned may not reassign a program manager or deputy program manager from such an assignment until after such major milestone has occurred.