U.S. Marine Corps Lance Cpl. Ethan Canden, a combat engineer with Kilo Company, 3rd Battalion, 1st Marines, holds security for a simulated improvised explosive device during Weapons and Tactics Instructors Course 1-18 at Yuma, Ariz., on Sept. 27, 2017. (Lance Cpl. Rhita Daniel/MArine Corps)
Staff Sgt. Gregory Corbitt, 19th Force Support Squadron NCO in charge of re-enlistments and extensions, pets Milo, 19th Airlift Wing morale dog, Sept. 21, 2017, at Little Rock Air Force Base, Ark. Milo went through several offices that day to increase morale and help airmen express themselves around chaplains and chapel staff members. (Airman Rhett Isbell/Air Force)
U.S. Marines and sailors with the 26th Marine Expeditionary Unit board a KC-130J Super Hercules with Marine Aerial Refueler Transport Squadron (VMGR) 252 on Sept. 27, 2017, at Marine Corps Air Station Cherry Point, N.C. VMGR-252 assisted the 26th MEU in providing aid and hurricane relief to Puerto Rico. (Lance Cpl. Cody J. Ohira/Marine Corps)
U.S. Army Sgt. Keith Jesmain, assigned to 12th Combat Aviation Brigade, observes out a UH-60 Black Hawk during the European Best Sniper Squad Competition at the 7th Army Training Command Grafenwoehr Training Area, Germany, Sept. 26, 2017. (Spc. Emily Houdershieldt/Army)
Naval Aircrewman (Helicopter) 2nd Class Brandon Larnard, assigned to Helicopter Sea Combat Squadron (HSC) 22, embarked aboard the amphibious assault ship USS Wasp (LHD 1), carries an evacuee off an MH-60S Sea Hawk helicopter on Sept. 27, 2017, following the landfall of Hurricane Maria on the island of Dominica. (MC3 Sean Galbreath/Navy)
Secretary of Defense Jim Mattis speaks to troops in Kandahar, Afghanistan, Sept. 28, 2017. (Air Force Staff Sgt. Jette Carr/DoD)
U.S. soldiers participate in the Polish national exercise Dragon 17 at the Bemowo Piskie Training Area, Sept. 26, 2017. (Sgt. Jimmy Golden/Army)
U.S. Army paratroopers assigned to 1st Battalion, 503rd Infantry Regiment, 173rd Airborne Brigade provides suppressive fire on Sept. 16, 2017, after an airborne operation during exercise September Heat 2017 at Rivolto Italian Air Force Base, Udine, Italy. (Visual Information Specialist Paolo Bovo/Army)
Marine Corps Lance Cpl. Alfredo Sandoval, an infantry Marine with Kilo Company, 3rd Battalion, 1st Marines, holds security for a rehearsal raid Sept. 27, 2017, during Weapons and Tactics Instructors Course 1-18 at Yuma, Ariz. (Lance Cpl. Rhita Daniel/Marine Corps)
Members of the 41st Airlift Squadron unload a C-130J upon returning from deployment Sept. 15, 2017, at Little Rock Air Force Base, Ark. Little Rock Airman returned after supporting Operation Freedom Sentinel and Operation Resolute Support. (Airman Rhett Isbell/Air Force)
The future littoral combat ship USS Little Rock (LCS 9) is underway during a high-speed run in Lake Michigan during acceptance trials Aug. 25, 2017. (Lockheed Martin via Navy)
Army Staff Sgt. Xavier Brooks, assigned to the 109th Transportation Company "Muleskinners," 17th Combat Sustainment Support Battalion, U.S. Army Alaska, issues orders to his soldiers while securing an objective during an exercise on Joint Base Elmendorf-Richardson, Alaska, Sept. 21, 2017. (Justin Connaher/Air Force)