A U.S. Marine carries a .50 caliber machine gun across the flight deck. A U.S. Marine assigned to the 13th Marine Expeditionary Unit embarked aboard the amphibious assault ship USS Boxer (LHD 4) carries a .50 caliber machine gun across the flight deck while the ship is underway in the Indian Ocean on June 24, 2009. The Boxer Amphibious Ready Group and the 13th Marine Expeditionary Unit are currently deployed in support of global maritime security. SHARE: Download: Full Size (0.03 MB) Credit: VIRIN: 313967-S-JVR72-690.jpg Photo Gallery