Since the Korean War in 1952-55, the United States has maintained a military presence in South Korea to deter aggression by North Korea and China.  Currently, the US operates some 15 military bases in the country with about 28,000 troops stationed there. These bases include two major air bases at Osan and Kunsan and the only US navy base in mainland Asia, Fleet Activities Base at Chinhae, which has about 170 active duty personnel and acts as a liaison for the South Korean navy.

This makes South Korea an Army/Air Force show almost exclusively.

Part of the Army and Air Force presence is constant training. Here are two cool videos from the Defence Department showing Apache helicopters and Blackhawks making their gunnery qualifications in South Korea.

In the video you will see them clearing jams from the M240 machine guns pretty often, this can be due to several things, not the least of which is firing long bursts which get the barrel and internal mechanism very hot while the ammunition is cold in the magazine box.  Generally, the M240 is pretty reliable with few jams, so this seems unusual. It could be a lack of lubrication, old ammo, headspace settings or improper loading.

Pilots assigned to 5-17 Air Cavalry Squadron and 4-2 Attack Battalion, 2nd Combat Aviation Brigade, 2nd Infantry Division, conduct aerial gunnery qualifications, July 23, 2022, Rodriguez Live Fire Complex, Republic of Korea. (U.S. Army video by Sgt. Oscar Toscano)

U.S. Army Soldiers from 2nd Battalion, 2nd Aviation Regiment, 2nd Combat Aviation Brigade, 2nd Infantry Division/ROK-U.S. Combined Division participate in dual door gunnery in their semi-annual door gunnery training exercise from June 21 to 25, 2022. U.S. Army Video by Capt. Frank Spatt