In contrast to USMA, here's a similar situation dealt with by the Naval Academy....

WP, 12 Jun 08: Draft Pick Must Serve 5-Year Active Duty
A Navy graduate drafted last week by the Cardinals was denied a bid to play ball yesterday and ordered to report for duty.

Mitch Harris, a newly commissioned ensign, must serve a five-year active duty commitment, Navy Secretary Donald C. Winter ruled.

"He will report to his ship as ordered," said Cmdr. Jeff Davis, a Navy spokesman.....