North Korea and South Korea exchange gunfire across the DMZ for the first time since 2017

North Korea and South Korea exchanged gunfire on Sunday across the Demilitarized Zone (DMZ), the heavily guarded border between the two countries, for the first time since 2017. There were no reports of injuries having emerged from the back-and-forth.

According to South Korea’s Yonhap News Agency, North Korea fired first — it’s unclear what prompted those shots, but US Secretary of State Mike Pompeo said Sunday on ABC’s This Week that “we think those are accidental.” A South Korean defense official told the Associated Press that the country also believes the shots were likely not a calculated decision.

South Korea’s military reported that gun shots from North Korea struck a South Korean guard post in the central border town of Cheorwon on Sunday morning. South Korea fired back with 20 warning shots, and then sent a warning broadcast, according to the South Korean military.

South Korean officials believe the chance of casualties in the North is unlikely, since the warning shots were fired into uninhabited territory. South Korea’s military personnel are unharmed.

The AP also reports that North Korea has not responded yet to South Korea’s warning message about trying to avoid escalation. So far, however, there are no signs of unusual troop movement in the North.

The gunfire exchange comes just days after North Korea’s leader, Kim Jong Un, appeared publicly for the first time in his country in 21 days — a notable absence from the public eye that stirred rumors that he was ill or perhaps even dead. And as Vox’s Alex Ward explained on Friday, it may never be clear why he was missing:

During this latest disappearance, there were unconfirmed reports that he’d undergone heart surgery and was recuperating — and perhaps that he was gravely ill due to complications from the surgery.

But it’s going to be near impossible to confirm that information, as Kim’s health is one of the most jealously guarded secrets in the country. Instead, Kim almost surely wants to change the subject, and showing up at a fertilizer plant as if nothing happened is one way to do just that.

Whether the activity at the border is at all related to this reappearance is not clear, but again, US and South Korean intelligence seems to suggest the gunfire was not a calculated move, particularly given that there haven’t been many exchanges at the DMZ — and no deadly ones — in recent years. The last time gunfire broke out along the border, in 2017, was when North Korea shot at a defector fleeing to the South, who survived.