U.S. soldiers man an M1A2 Abrams tank concealed by a hull-down battle position during Exercise Peace Sentinel at Novo Selo Training Center, Bulgaria, Nov. 23, 2015. U.S. Army photo by Staff Sgt. Steven M. Colvin
Marines are being lifted to a height of over 350 feet in the air to avoid any possible obstacles before flying around the area during insertion and extraction rigging training on Camp Pendleton, Calif., Nov. 19, 2015. U.S. Marine Corps photo by Cpl. Briauna Birl
Marines land on the airfield after taking a ride during Special Patrol Insertion and Extraction rigging training on Camp Pendleton, Calif., Nov. 19, 2015. U.S. Marine Corps photo by Cpl. Briauna Birl
A U.S. Army Special Operations Forces parachute team member descends toward Luzon drop zone during the 18th Annual Randy Oler Memorial Operation Toy Drop on Camp Mackall, N.C., Dec. 7, 2015. Operation Toy Drop is the world's largest combined airborne operation during which service members help provide children in need with toys for the holidays. U.S. Air Force photo by Staff Sgt. Douglas Ellis
U.S. paratroopers sit inside a U.S. Air Force C-130 Hercules aircraft awaiting takeoff on Aviano Air Base, Italy, Dec. 2, 2015. U.S. Army photo by Paolo Bovo
Wreaths adorn headstones following the annual Wreaths Across America event in Arlington National Cemetery, Arlington, Va., Dec. 12, 2015. Volunteers with the nonprofit organization placed a wreath on every eligible headstone in the cemetery to remember and honor the fallen. U.S. Army photo by Rachel Larue
U.S. Navy Seaman Anthony Fabiochi signals the Military Sealift Command fleet replenishment oiler USNS Leroy Grumman for more cargo during a replenishment at sea with USS Carney in the Mediterranean Sea, Dec. 7, 2015. Fabiochi is a boatswain’s mate. The Carney is conducting a routine patrol in the U. S. 6th Fleet area of operations to support U.S. national security interests in Europe. U.S. Navy photo by Petty Officer 1st Class Theron J. Godbold
Wreaths lay in the columbarium following the annual Wreaths Across America event in Arlington National Cemetery in Arlington, Va., Dec. 12, 2015. U.S. Army photo by Rachel Larue
A U.S. Marine fast-ropes out of an SH-60 Seahawk helicopter aboard the amphibious assault ship USS Kearsarge in the North Red Sea, Nov. 5, 2015. U.S. Marine Corps photo by Cpl. Jalen D. Phillips
An MH-60S Seahawk helicopter prepares to land on the flight deck of the USS George Washington in the Atlantic Ocean, Nov. 17, 2015. The George Washington was participating in UNITAS, the U.S. Navy's longest-running annual multinational maritime exercise. U.S. Navy photo by Petty Officer 3rd Class Paul Archer