A U.S. Marine gives a brief prior to beginning the Amphibious Combat Endurance Test on Marine Corps Base Camp Pendleton, Calif. Jan. 15. - A U.S. Marine gives a brief prior to beginning the Amphibious Combat Endurance Test on Marine Corps Base Camp Pendleton, Calif. Jan. 15.

U.S. Marines conduct fast roping during exercise Forest Light Eastern Army in mainland Japan, Dec. 10. - U.S. Marines conduct fast roping during exercise Forest Light Eastern Army in mainland Japan, Dec. 10.

U.S. Marines fire an M2 .50 caliber machine gun on Camp Hansen, Okinawa, Japan, Aug. 26. - U.S. Marines fire an M2 .50 caliber machine gun on Camp Hansen, Okinawa, Japan, Aug. 26.

A Marine with U.S. Marine Corps Forces Special Operations Command rappels off the ramp of a CH-53E Super Stallion with Marine Heavy Helicopter Squadron 461 on Landing Zone Parrot at Marine Corps Base Camp Lejeune, N.C., July 20, 2016. The exercise was a part of a two weeklong Helicopter Insertion and Extraction Techniques Course. The CH-53 provided for the training evolution was assigned to Marine Heavy Helicopter Squadron 461, 2nd Marine Aircraft Wing. - A Marine with U.S. Marine Corps Forces Special Operations Command rappels off the ramp of a CH-53E Super Stallion with Marine Heavy Helicopter Squadron 461 on Landing Zone Parrot at Marine Corps Base Camp Lejeune, N.C., July 20, 2016. The exercise was a part of a two weeklong Helicopter Insertion and Extraction Techniques Course. The CH-53 provided for the training evolution was assigned to Marine Heavy Helicopter Squadron 461, 2nd Marine Aircraft Wing.

Marines with 2nd Battalion, 5th Marine Regiment, Weapons Company, Scout Sniper Platoon, fast rope from an MV-22B Osprey with Marine Medium Tiltrotor Squadron 164 aboard Marine Corps Base Camp Pendleton, Calif., June 30. The ability to fast rope enables Marines to insert into an area or structure without landing the aircraft, eliminating the need for a landing zone. - Marines with 2nd Battalion, 5th Marine Regiment, Weapons Company, Scout Sniper Platoon, fast rope from an MV-22B Osprey with Marine Medium Tiltrotor Squadron 164 aboard Marine Corps Base Camp Pendleton, Calif., June 30. The ability to fast rope enables Marines to insert into an area or structure without landing the aircraft, eliminating the need for a landing zone.

Capt. Joseph Tremaine, a CH-53E Super Stallion pilot with Marine Heavy Helicopter Squadron (HMH) 466, conducts preflight checks aboard Marine Corps Air Station Miramar, California, July 2. The aircrew prepares the aircraft for night fast-rope training on Marine Corps Base Camp Pendleton, California. - Capt. Joseph Tremaine, a CH-53E Super Stallion pilot with Marine Heavy Helicopter Squadron (HMH) 466, conducts preflight checks aboard Marine Corps Air Station Miramar, California, July 2. The aircrew prepares the aircraft for night fast-rope training on Marine Corps Base Camp Pendleton, California.

Cpl. Caleb Owens, from Melbourne, Iowa, prepares to fast-rope out of an MV-22B Osprey tiltrotor aircraft with his military working dog, Dixie, Oct. 27 at Camp Hansen. After familiarizing themselves with fast-roping techniques by executing them with no gear, the Marines worked their way up to wearing full gear and then with their military working dogs as well. Owens is a military policeman, and a working dog handler. He and Dixie are with 3rd Law Enforcement Battalion, III Marine Expeditionary Force Headquarters Group, III MEF. - Cpl. Caleb Owens, from Melbourne, Iowa, prepares to fast-rope out of an MV-22B Osprey tiltrotor aircraft with his military working dog, Dixie, Oct. 27 at Camp Hansen. After familiarizing themselves with fast-roping techniques by executing them with no gear, the Marines worked their way up to wearing full gear and then with their military working dogs as well. Owens is a military policeman, and a working dog handler. He and Dixie are with 3rd Law Enforcement Battalion, III Marine Expeditionary Force Headquarters Group, III MEF.