U.S. Marine Corps Sgt. Yer Lee, right, data network

U.S. Marine Corps Sgt. Yer Lee, right, data network specialist, 1st Battalion, 6th Marine Regiment, 2nd Marine Division (MARDIV), stands at attention as he is promoted to sergeant, during a promotion ceremony prior to the start of Mountain Exercise 5-15 at the Marine Corps Mountain Warfare Training Center, Bridgeport, Calif., Sept. 2, 2015. Marines participate in a month-long field exercise focusing on core mission essential tasks such as assault climbing, animal packing and small unit movements, to strengthen expeditionary high altitude warfare tactics in a mountainous environment against a hybrid threat, as they prepare for world-wide deployment. (U.S. Marine Corps photo by Cpl. Kelly L. Street, 2D MARDIV COMCAM/Released)