Explainer: What is the Joint Security Area between North and South Korea?

A US soldier was detained by North Korea on Tuesday after he crossed into the country “wilfully and without authorisation”, according to a US official.

The soldier, Private 2nd Class Travis King, crossed the military demarcation line that separates the two countries while on a tour of the Joint Security Area (JSA) between North and South Korea. He is the first American detained in North Korea in five years.

What is the Joint Security Area?

Also known as Panmunjom or the “peace” or “truce” village, the JSA is a section on the 250km-long Demilitarized Zone separating North and South Korea.

Map of North and South Korea

In 1948, when the Democratic People’s Republic of Korea (North Korea) and the Republic of Korea (South Korea) were created, the DMZ marked the border between the two countries. In 1950, North Korea invaded South Korea, starting the Korean war, which ended in an armistice in 1953, signed at the JSA, at which point the DMZ became a 2km-wide buffer zone. The DMZ is lined on both sides with razor wire, heavy armaments and tank traps.

A North Korean soldier stands guard on the North Korean side of the Joint Security Area in the Demilitarised Zone (DMZ). Photograph: Carl Court/Getty Images

The peace village is made up of bright United Nations-blue buildings, bisected by a military demarcation line. The two Koreas have their own liaison offices and conference halls in the JSA and troops from each country face each other across the military demarcation line, but despite working in close quarters, communication is often strained.

During periods of high tensions phone hotlines often go unanswered, forcing US or South Korean officials to try to shout across the border.

For years, both sides also blared propaganda broadcasts over the DMZ into each other’s territory. The broadcasts ended after a 2018 military agreement.

The JSA is overseen by North Korea and the UN Command, a multinational military force established during the Korean war.

In 2018, North Korean leader Kim Jong-un and South Korean president Moon Jae-in met on the north and south sides of Panmunjom. In 2019, US president Donald Trump became the first incumbent president to enter North Korea, when he travelled to the JSA, crossed the military demarcation line on foot and shook hands with Kim.

Kim Jong-un meets Donald Trump in the Joint Security Area Photograph: KCNA/KNS/AFP/Getty ImagesCan you visit the JSA?

Under a 1953 deal, the UN Command and the North Korean military were allowed to send no more than 35 troops to the JSA, and each of them can only possess one pistol or non-automatic rifle. But the number of soldiers and weapons increased as relations worsened. No civilians live in the JSA.

Vast stretches of the DMZ have been no man’s land for more than 60 years, where wildlife has flourished undisturbed. Other parts of it offer an unsettling mix of military installations and tourist attractions.

Multiple companies offer tourists visiting South Korea the chance to visit the JSA. Lonely Planet describes it as “unquestionably the highlight of any trip to the DMZ” during which, “You’ll be taken inside the meeting room – where the 1953 truce was signed – the only place where you can safely walk into North Korea”.

North Korean soldiers (C) take photos of a South Korean soldier (L) and a US soldier (R) standing before the military demarcation line separating North and South Korea. Photograph: Ed Jones/AFP/Getty Images

It was while on one of these tours that US soldier Travis King crossed the border. The Donga and Chosun Ilbo newspapers cited South Korean army sources who claimed the man was with a group of visitors, including civilians, to the Panmunjom truce village “when he suddenly bolted over the brick line marking the border”.

The DMZ is littered with landmines planted over the decades, as many as 970,000 in the southern part alone, according to Landmine and Cluster Munition Monitor, a Geneva-based civic group.

Why did the US soldier cross the military demarcation line?

That remains unclear. King had served nearly two months in a South Korean prison for assault. He was released and was meant to travel home to Fort Bliss, Texas, where he faced further disciplinary action. After being escorted to the airport, he left and joined a tour to the JSA.

The US is working with North Korea to “resolve this incident”, said White House press secretary Karine Jean-Pierre. The detention comes amid heightened tensions between the US and North Korea over Pyongyang’s increasing nuclear capabilities.

Reuters contributed to this report