U.S. and South Korea send thousands of troops and 23-ton vehicles to practice beach assault

North Korea has been building up a ballistic missile arsenal on the stated premise that it needs to deter an attack on it by United States and South Korean forces.

Washington and Seoul have been showing their firepower through an increasing number of exercises, all of which the two allies say are defensive in nature.

But on Wednesday morning, they used thousands of troops and high-end weaponry to practice an amphibious assault, a manoeuvre offensive in its nature and designed to take territory, not defend it.

The commander of the 2,200 U.S. Marines involved in Exercise Ssang Yong in Pohang on the southern coast of South Korea defends what's taking place as not provocative.

"I don't think we're doing anything different or odd," said Col. Samuel Meyer, commander of the 13th Marine Expeditionary Unit.

The exercise put the integrated firepower of U.S. and South Korean forces on full display.

Seoul's Marines came ashore first in waves of 23-ton amphibious assault vehicles, their tracks leaving foot-deep gashes in the Pohang sands.

As the South Korean Marines moved to a tree line behind the beach, huge U.S. Navy hovercraft, known as LCACs, followed, disgorging eight-wheeled amphibious vehicles with nicknames like "Rooster", "Cerberus" and "Ghost" stenciled on their sides.

In the skies above were attack helicopters, Osprey transports and F-35B stealth fighters, 10 of which were embarked aboard the amphibious assault ship USS Makin Island, lurking 30 miles off shore.

"This is the 70th anniversary of this exercise. It's not new," Meyer said, dismissing claims by Pyongyang that Washington and Seoul are being provocative and forcing North Korea to build up its nuclear program as deterrence.

"This is routine. We're just getting back to the routine, based on what we saw and experienced," the U.S. Marine colonel said.

'ANYTIME, ANYWHERE'

But little seems routine on the Korean Peninsula or in wider East Asia in 2023.

As Meyer spoke with reporters aboard the 45,000-ton USS Makin Island, essentially a baby aircraft carrier, on Tuesday, an actual 98,000-tonne U.S. Navy aircraft carrier, the USS Nimitz, was conducting operations of its own off the peninsula.

Closer to the Pohang beach, at least six South Korean naval vessels could be seen in support, sending troops ashore for Exercise Ssang Yong.

Meanwhile, North Korean state media was releasing pictures of leader Kim Jong Un inspecting what it claimed were nuclear weapons, and calling on his forces to be able to use them "anytime and anywhere."

To the north, Russia, a North Korean ally, was launching cruise missiles at a target in the waters off the east coast of the Korean Peninsula.

And a Russian intelligence ship was keeping an eye on the Makin Island and the rehearsal for Wednesday's exercise, sitting just 15 miles from the Makin Island, said the ship's commander, Navy Capt. Tony Chavez.

The Russian ship was doing exactly what Chinese naval vessels did when the Makin Island and the ships deployed with it -- the amphibious landing docks USS Anchorage and USS John P. Murtha -- did when the U.S. warships were in the South China Sea before coming to Korea, keeping an eye on their every move from 12 to 15 miles away, Chavez said.

Exercise Ssang Yong hadn't been done in five years, initially due to a break for diplomacy and then for the Covid pandemic.

But in the past year Pyongyang has been testing ballistic missiles at a record rate with Kim Jong Un ordering practice nuclear strikes on targets in the South. With Kim's belligerence, the U.S. have South Korea have been stepping up their preparedness to respond to any North Korean aggression.

AMPHIBIOUS LANDING INFUSED WITH SYMBOLISM

Tensions on the Korean Peninsula have been on edge since talks between then-U.S. President Donald Trump and North Korean leader Kim Jong Un failed to produce an agreement after three meetings between the two, the last in 2019.

Kim has since ratcheted up his ballistic missile program, last year testing the weapons on an average of more than three times a month.

The testing has continued this year, with Pyongyang most recently testing what it said were nuclear-capable cruise missiles and a nuclear-capable underwater drone last week.

But the growing military activity hasn't only been north of the demilitarized zone separating North and South Korea.

The Korean Peninsula has been a hotbed of military activity for much of this year and especially in the past month as U.S. and South Korean forces have been conducted "Operation Freedom Shield," the largest military exercises between the two allies since 2018, when military displays were curtailed to encourage Kim to backtrack on the North's nuclear program.

Looking back to the Korean War can give a little perspective on why amphibious landings have raised temperatures in Pyongyang so much.

North Korea lost its advantage in that war due to one.

The 1950 Battle of Incheon is considered one of the most successful amphibious assaults in military history

In that engagement U.S. and allied warships bombarded the North Korean-held port of Incheon for two days before U.S. Marines stormed ashore at three beaches 110 miles behind North Korean lines in a bid to force Pyongyang's troops out of the South Korean capital of Seoul, 31 miles (50 kilometers) to the west.

The beachhead was quickly established and less than two weeks later, with the help of South Korean and other U.S. forces attacking from the south, Seoul was back in allied hands.

That U.S.-South Korean cooperation eventually yielded the military relationship seen on the peninsula today.

Key U.S. military installations now dot South Korea. Among them is the U.S. Army's Camp Humphreys, the largest U.S. military installation outside of the United States with a population of more than 36,000 U.S. service members, civilian workers, contractors and family members.

Last October, North Korea practiced procedures that could initiate a tactical nuclear strike on "the enemies' main military command facilities," according to North Korea state media.

And those kinds of threats are a key reason exercises like Ssang Yong are necessary, U.S. commanders say. The American and South Korean militaries need to be one cohesive unit.

"We have to be prepared for whatever changes may happen ... building that strong relationship and that strong alliance for whatever changes that we cannot control," Meyer said.