South Korean Marines watch the beach during a landing exercise in Pohang, South Korea, Sept. 2, 2024. (Luis Garcia/Stars and Stripes)

POHANG, South Korea — Explosions rang out on the beach and fifth-generation fighter jets flew overhead as U.S. and South Korean marines and sailors practiced an amphibious assault on South Korea’s southeastern coast this week.

About 9,500 marines and sailors, along with 3,500 of their South Korean counterparts, are taking part in this year’s Ssangyong exercises in Pohang, a coastal city about 150 miles below Seoul. Ssangyong, which began Aug. 26, means “twin dragons” and refers to the cooperating armies. The exercise ends Saturday.

The approaching Marines faced foot-high waves and strong winds, while short-lived rain showers soaked the beach and made it difficult for them to move.

South Korean Marines take up positions during a mock amphibious assault on a beach in Pohang, South Korea, Sept. 2, 2024. (Luis Garcia/Stars and Stripes)

This year’s annual exercise brought two Marine expeditionary units to South Korea, not just one. The Corps’ recently introduced landing combat vehicle was also used for the first time on the Korean peninsula.

Monday’s simulated naval assault featured a range of U.S. and South Korean military hardware, which allies describe as a defensive effort to enhance joint operations on land, in the air and at sea.

Shock waves from explosive charges planted on the beachhead sent sand, seawater, and seaweed into the air, simulating the initial bombardment by aircraft and warships prior to the afternoon landing operation.

American and South Korean F-35B Lightning II fighters flew over the beach, followed by a fleet of MV-22 Osprey aircraft and UH-1Y Venom and AH-1Z Viper helicopters.

South Korean F-35B Lightning II stealth fighters fly over the city of Pohang, South Korea, during a mock amphibious landing, Sept. 2, 2024. (Luis Garcia/Stars and Stripes)

They were followed by South Korean C-130H aircraft that dropped several dozen Marines on a landing zone about a mile away.

Less than an hour after the first explosions, South Korean warships moored nearby unloaded more than a dozen South Korean landing craft. The stream of vehicles traveled single file for 15 to 20 minutes before reaching the beachhead. South Korean marines jumped out of the crawlers and took cover in the dunes, weapons drawn.

The U.S. Marines arrived in their combat vehicles at a separate, nearby beachhead due to safety concerns after worsening weather conditions prompted a last-minute change of plans, 3rd Marine Expeditionary Brigade spokesman Maj. George McArthur told the Stars and Stripes on Monday.

This year, the Marines combined two expeditionary units for the exercise: the 15th MEU from Camp Pendleton, California, and the 31st MEU from Okinawa, McArthur said.

“Trying these types of combined amphibious entry operations and then continuing to land operations is very important because of the complexity of them,” 31st MEU commander Lt. Col. Gabriel Tiggs told reporters Monday. “The defense of the Korean Peninsula depends on our (South Korean) and American forces working together, shoulder to shoulder, on a continuing basis, including this and future Ssangyong exercises.”

A South Korean marine takes up position during a mock amphibious assault on a beach in Pohang, South Korea, Sept. 2, 2024. (Luis Garcia/Stars and Stripes)

The airborne training comes on the heels of Ulchi Freedom Shield, a large-scale 11-day joint exercise across South Korea. The six-month training, which ended Thursday, focused on specific threats from North Korea, including GPS jamming, cyberattacks, airborne signal interception and ground combat, according to South Korea’s Ministry of National Defense.

McArthur said Ssangyong is not tailored to the needs of any particular country, adding that the U.S. and South Korean militaries are “always looking to enhance a progressive set of capabilities and processes to be able to work together.”

An AC-130 attack aircraft drops South Korean paratroopers during a mock amphibious assault on a beach in Pohang, South Korea, Sept. 2, 2024. (Luis Garcia/Stars and Stripes)