The JSA, has seen other instances of sudden violence in the sixty years since a 1953 armistice brought an uneasy and often imperfect peace to the two Koreas.
The centrepiece of the JSA is a circular garden which was the site of a 1984 firefight when a visiting Russian attempted to defect.
Even in recent months shots have been fired in anger around the JSA.
One of the guides for visitors is US Infantry Private Cody Krupicka.
Private Krupicka is one of the soldiers selected from the 28,000 US troops still stationed in Korea by reason of their "above average aptitude" to work in the highly charged environment of the JSA and surrounding area.
Yesterday he told the Herald of an incident last October when a North Korean soldier on a night patrol turned his gun on his commander before fleeing across a minefield. The would-be defector "banged on one of our soldier's doors" seeking asylum.
The JSA is also a battleground of crude symbolism.
When South Korea put up a flagstaff of 100m height, the North Koreans erected one 160m high.
When the South Koreans built "Freedom House", a building intended - but almost never used - as a place where families separated by the border could briefly meet, the North Koreans added an extra storey to their corresponding building opposite so it wouldn't be dwarfed.
Lying between those two buildings is conference row, a line of huts which straddle the border.
They include building "T2" where the armistice was signed after negotiations that dragged on for so long that one particular 11 hour session became known as "the bladder war".
Next door is building formally known as a recreation centre. However it is used by North Koreans to watch what is happening in T2. Because of the rude and ridiculous gestures they make to visitors and their South Korean counterparts through its windows, it is popularly known as "The Monkey House".
Lieutenant Commander Ian Marshall, one of three New Zealand Army personnel stationed nearby is the DMZ operations officer. His job is to monitor compliance with the terms of the armistice.
"There's always potential for threat," he told New Zealand media visiting the DMZ yesterday.
He's not necessarily concerned about that, "but you know that at any time anything could set anything off".