((a)) ** .—** A person who has been convicted of an offense specified in subsection (b) under Federal or State law may not be processed for commissioning or permitted to enlist in the armed forces.

((b)) ** .—** An offense specified in this subsection is any felony offense as follows:

((1)) Rape or sexual assault.

((2)) Forcible sodomy.

((3)) Incest.

((4)) An attempt to commit an offense specified in paragraph (1) through (3), as punishable under applicable Federal or State law.