A Marine runs towards his assault position under the cover of smoke during a battalion-wide exercise coordinated with Korean-based U.S. Army units June 9 at the Rodriguez Live Fire Complex near the Demilitarized Zone. The complex exercise marked the final stage of the Unit Deployment Program for the Camp Lejeune-based Marines from 3rd Battalion, 2nd Marine Regiment. (Matthew M. Burke/Stars and Stripes)

Lance Cpl. Jordan Hefner bursts into a room during a dry run through the Rodriguez Live Fire Complex's shoot-house, South Korea, in June. (Matthew M. Burke/Stars and Stripes)

A decommissioned tank overlooks the Rodriguez Live Fire Complex near the Demilitarized Zone in South Korea. The joint American-South Korean base hosted Marines from 3rd Battalion, 2nd Marine Regiment in June for live-fire training and a battalion-wide exercise performed in conjunction with South Korean-based U.S. Army units. (Matthew M. Burke/Stars and Stripes)

Prior to the battalion-wide exercise on June 9, 2015, where Marines were supported by South Korean-based U.S. Army Apache attack helicopters, the 3rd Battalion, 2nd Marine Regiment troops were given the opportunity to inspect the birds that would be flying overhead. Here, two Marines look closely at the Apache's chain gun. (Matthew M. Burke/Stars and Stripes)

Marine Sgt. Jeremy Plympton checks out the controls in a U.S. Army Apache attack helicopter ahead of a battalion-wide exercise on June 9, 2015, in South Korea. (Matthew M. Burke/Stars and Stripes)

A group of Marines juggle a homemade hacky sack outside the barracks during downtime at Rodriguez Live Fire Complex near the Demilitarized Zone in June. Like actual combat, their time at Rodriguez was marked by long stretches of boredom, punctuated by short bursts of extreme action. (Matthew M. Burke/Stars and Stripes)

Lance Cpl. John Brooks Jr. enters the live-fire shoot-house at Rodriguez Live Fire Complex near the Demilitarized Zone in June. The Marines were closely scrutinized from behind and from above as they moved through the house, clearing rooms, and eliminating enemy targets. (Matthew M. Burke/Stars and Stripes)

Marines from Company I line up to enter the Rodriguez Live Fire Complex's live-fire shoot-house in June 2015 in South Korea. (Matthew M. Burke/Stars and Stripes)

Sparks fly on impact as a Marine eliminates targets in a room-clearing exercise at the Rodriguez Live Fire Complex's live-fire shoot-house in June. (Matthew M. Burke/Stars and Stripes)

A Marines closes on his target at the Rodriguez Live Fire Complex's live-fire shoot house in June 2015 in South Korea. (Matthew M. Burke/Stars and Stripes)

Marines clear a room at the Rodriguez Live Fire Complex's live-fire shoot-house in June. The 3rd Battalion, 2nd Marine Regiment troops were on the final phase of their Unit Deployment Program. (Matthew M. Burke/Stars and Stripes)

Marines storm the Rodriguez Live Fire Complex's live-fire shoot-house in June. The Camp Lejeune-based unit grunts were in the final phase of the Unit Deployment Program. (Matthew M. Burke/Stars and Stripes)

First Lt. Billy Grissom III, left, and 1st Lt. Miles Essay watch as a mortar hits its target halfway up the mountain in front of them during a battalion-wide exercise June 9, 2015, at the Rodriguez Live Fire Complex near the Demilitarized Zone. (Matthew M. Burke/Stars and Stripes)

Lance Cpl. Khadeem Jeffers, a weapons platoon mortarman, releases a mortar into the tube during a battalion-wide exercise June 9, 2015, at the Rodriguez Live Fire Complex near the Demilitarized Zone. (Matthew M. Burke/Stars and Strip)

Lance Cpl. Khadeem Jeffers, right, ducks as a mortar fires during a battalion-wide exercise June 9 at the Rodriguez Live Fire Complex, south Korea. Cpl. Cody Johansen, left, readies another round. (Matthew M. Burke/Stars and Stripes)

Newly minted Cpl. Eduardo Rodriguez used his boonie cap as a frisbee while waiting several hours for a battalion-wide exercise to commence June 9, 2015, at the Rodriguez Live Fire Complex, South Korea. (Matthew M. Burke/Stars and Strip)

Lance Cpl. Trevon Nottage catches a few winks while holding his mortar tube in the back of a 7-ton transport vehicle June 9, 2015, while waiting for a battalion-wide exercise to commence in South Korea. (Matthew M. Burke/Stars and Stripes)

Marines can sleep anywhere. Here, they catch a few winks while waiting for a battalion-wide exercise to commence. (Matthew M. Burke/Stars and Stripes)

Marines sleep on the hard ground while waiting several hours for a battalion-wide exercise to commence in South Korea. (Matthew M. Burke/Stars and Stripes)