UPDATE 1-U.S. GAO dismisses Lockheed protest of $6.75 bln Oshkosh Army deal

WASHINGTON, Dec 15 (Reuters) - The U.S. Government Accountability Office on Tuesday dismissed Lockheed Martin Corp's protest of a $6.75 billion Army contract for next-generation Humvees to Oshkosh after Lockheed said it would take the issue to federal court.