Dual sovereignty in action

Despite the constitutional protection against double jeopardy, it is possible under the "dual sovereignty" doctrine for the same conduct to be punished by both the federal government and a state. The principle applies regardless of whether the first trial resulted in a conviction or an acquittal. Here's a current example involving a sailor who was convicted in state court and served time for unpremeditated murder and is now facing military prosecution. See also this report from The Virginian-Pilot.

What is your reaction? What interest of the Navy does this second prosecution vindicate, other than second-guessing whether the state sentence, which reflected a plea bargain, was inadequate?