The joint investigation into the Sept. 21 explosion inside the Demilitarized Zone near Paju begins Sunday, Sept. 27, pulled forward two days from a Sept. 29 start after opposition lawmakers accused the government of leaving the site unexamined for the better part of a week.
Three people were injured in the blast. The United Nations Command had pressed for a prompt probe. The Joint Chiefs of Staff entered the DMZ on Sept. 26 to prepare the ground for the joint team, an entry distinct from the JCS inspection reported the same day.
What is confirmed
Confirmed: the explosion happened Sept. 21 inside the DMZ near Paju; three people were injured; the UNC sought an early investigation; the JCS crossed into the zone on Sept. 26 for environmental and safety preparation; and the joint ROK–UNC team now starts Sept. 27 instead of Sept. 29.
Not confirmed: the device type, how it was placed, who placed it, and whether the original Sept. 29 date reflected logistics inside a controlled military zone or a decision to wait. The government has not published a public rationale for the first date.
The five-day gap between the blast and the first ROK entry is the factual core of the delay argument. It is also the one number both sides are working from.
Who holds the file
Two chains run in parallel. The JCS holds the ROK military's operational file — patrol schedules, unit reports, the immediate response on Sept. 21. The UNC, as the command that administers movement inside the DMZ under the armistice framework, controls site access and carries its own investigative interest as a signatory.
A joint probe is the mechanism that lets both work the same ground without either side claiming primacy. In practice that means shared site security, agreed marking of the blast area, documented sample collection, and a chain of custody both commands sign off on before anything is tested off-site.
For anyone asking which Korean agency owns the case, the answer is neither a police station nor a prosecutors' office. Inside the DMZ, the file moves through the military chain, with the armistice structure sitting above it.
The liability question
Korean law punishes the unlawful placement of explosives and the injuries that follow, and the ROK military maintains a separate disciplinary track for negligence on duty. Neither maps cleanly onto a blast inside the DMZ.
The zone is not ordinary territory. Status-of-forces arrangements govern foreign personnel, the armistice governs who may enter and when, and both constrain how evidence is gathered and preserved for any later proceeding. If the findings point to a deliberately emplaced device, the practical target is a state rather than an individual within reach of a Korean court.
There is a precedent. The 2015 mine blasts inside the DMZ that injured two ROK soldiers produced a military response and a loudspeaker campaign, not a criminal prosecution. The legal channel and the retaliation channel ran separately then, and the same split is likely here.
The nearer exposure is institutional. If the site sat long enough for the scene to degrade, the question shifts from who planted the device to who controlled the ground and when — which is exactly where Han Dong-hoon and the opposition have aimed, arguing the Lee government cannot defend the DMZ.
What to watch
Three signals. First, whether the joint team releases a device assessment rather than a summary statement. Second, whether the JCS and UNC describe the Sept. 21–26 gap the same way. Third, whether the Sept. 27 start holds if weather or safety conditions on the ground change.
Until a forensic result is published, the verified record is thin: a date, a location, three injuries, and a schedule moved up by two days. The claim of deliberate delay remains contested, and the answer will come from the ground, not from the press statements.