((a)) Leave for not more than 90 days may be authorized, in the discretion of the Secretary concerned, or his designated representative, to a member of an armed force who reenlists. Leave authorized under this section shall be deducted from leave accrued during active service before reenlistment or charged against leave that may accrue during future active service, or both.

((b)) Under regulations prescribed by the Secretary of Defense, and notwithstanding subsection (a), a member who is on active duty in an area described in section 310(a)(2) or paragraph (1) or (3) of and who, by reenlistment, extension of enlistment, or other voluntary action, extends his required tour of duty in that area for at least six months may be—

((1)) authorized not more than thirty days of leave, exclusive of travel time, at an authorized place selected by the member; and

((2)) transported at the expense of the United States to and from that place.