Why Are North Korean Soldiers Crossing the DMZ?

A barbed-wired fence is seen at the Imjingak Pavilion, near the demilitarized zone (DMZ) in Paju, South Korea, on July 19, 2023.

Despite its name, the Demilitarized Zone (DMZ) between North and South Korea is one of the most heavily fortified places on Earth. Two million landmines, barbed wire fences, tank traps, and tens of thousands of troops from both countries patrol a 248-kilometer (154-mile) long, 4-kilometer (2.5-mile) wide strip of land.

So how do North Korean soldiers continue to wander across the border, prompting South Korea to fire warning shots for the third time this month?

The answer seems to be dense foliage: The North Koreans may have been unable to see the signs marking the thin military demarcation line due to overgrown vegetation.

But this is just the latest chapter in the long, often violent history of the unique border established after the 1950-53 Korean War. The war ended with an armistice rather than a peace treaty, leaving the Korean Peninsula divided and technically still at war.

Here’s a look at the events surrounding the incursion:

What happened?

South Korea’s military reported that they fired warning shots on Thursday to repel several North Korean soldiers who briefly crossed the military demarcation line during unspecified construction work.

Seoul’s Joint Chiefs of Staff said the North Koreans retreated after South Korean soldiers issued a warning and fired the shots Thursday morning but did not immediately release further details.

Similar incidents occurred on June 9 and June 18, each involving 20 to 30 North Korean soldiers briefly crossing the demarcation line and retreating soon after South Koreans issued audio warnings and fired warning shots.

South Korea’s military asserts that the incursions were likely accidental, noting that the North Koreans did not return fire and withdrew promptly.

What does the demarcation line look like?

In many parts of the DMZ, the demarcation line is simply a sign mounted on a stick or a piece of concrete.

People have crossed it before, under very specific circumstances, and usually at the border village of Panmunjom. Former U.S. President Donald Trump walked across with Kim Jong Un. Last year, an American soldier facing potential military discipline dashed across the line to the North.

Outside of Panmunjom, much of the DMZ is wilderness, but it is heavily monitored on both sides. While the demarcation line may be easily crossed, it’s very difficult to do so without being spotted immediately.

The southern side of the land border is protected not only by thousands of soldiers, guns, and mines but also by a dense network of cameras, motion sensors, and other high-tech surveillance equipment. Breaches are rare and usually detected quickly. Defections from the North are also unusual along the North-South land border, though they have happened frequently along the porous China-North Korea border and occasionally in the Yellow Sea.

The North’s accidental intrusions this month may have been caused by a sudden increase in North Korean troops fortifying their side of the border.

Seoul says overgrown trees and plants may have obscured the signs marking the demarcation line, causing the North Korean troops to cross without realizing it.

Why are so many North Koreans working in the DMZ?

Relations between the rival Koreas are worse now than they have been in many years.

Recent weeks have seen a tit-for-tat standoff that has resulted in Cold War-style psychological warfare. Both sides have stated they are no longer bound by a landmark 2018 military agreement to reduce tensions.

Seoul reports that the North Koreans along the border have been installing what appear to be anti-tank barriers, reinforcing roads, and planting landmines, even as mine explosions have killed or wounded an unspecified number of North Korean soldiers.

The construction began around April and may be an attempt to curb North Koreans trying to defect to the South, according to Seoul’s military.

Animosities may worsen as Kim continues to accelerate his nuclear weapons and missiles development and aligns with Russian President Vladimir Putin in the face of their separate, escalating confrontations with Washington.

On Thursday, South Korea’s government condemned an agreement by Kim and Putin at their summit this week in which the two nations pledged to aid each other if attacked. In turn, Seoul said it would consider sending arms to Ukraine to help it fight Russia’s invasion.

Could it happen again?

Possibly, especially if the North Korean construction continues along the demarcation line.

But both sides seem intent on limiting their animosity to the psychological warfare they are engaging in.

Still, there are concerns that the hostilities are pushing them closer to a direct military clash. The Koreas have not had any meaningful talks for years and might find it difficult to initiate dialogue as tensions rise over the North’s development of nuclear-capable weapons.

Some analysts believe the Koreas’ poorly marked western sea boundary—site of skirmishes and attacks in past years—is more likely to be a crisis point than the land border.

Kim, in a fiery speech in January, reiterated that his country does not recognize the Northern Limit Line in the Yellow Sea, which was established by the U.S.-led U.N. Command at the end of the war. North Korea insists on a boundary that encroaches deeply into South Korea-controlled waters.

While the massive military presence on both sides of the DMZ means that years sometimes pass without incident, violence can quickly erupt. For example, two American Army officers were axed to death in 1976 by North Korean soldiers.

—Kim reported from Seoul. Klug, AP’s news director for the Koreas, reported from Tokyo.