Miranda Rights on the Battlefield Unconstitutional?

Soldiers have been ordered to issue battlefield Miranda rights to captured enemy combatants.

Rick Moran does an excellent job explaining the trouble with issuing Miranda rights to terrorists.

The administration, though, is in a pickle. Even if enemy combatants were issued Miranda rights on the battlefield, were they issued consistent with the Constitution?

Under Article I, Section 8[11] of the Constitution, only Congress is authorized: "To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water."

If the Miranda rights were ordered by the administration without congressional authorization, are they unconstitutional?

Eric Holder had better identify explicitly the congressional authority, otherwise this may be yet another way for terrorists to escape justice under Article III courts.