SEOUL, July 23 (UPI) — South Korea’s Joint Chiefs of Staff on Thursday warned that landmines laid by North Korea in the Demilitarized Zone may have been washed into the South after recent heavy rainfall.

“There is a very high possibility that these washed-away landmines could flow into our territory via the rivers shared between the two Koreas, and an explosion of these landmines could cause significant damage,” JCS spokesman Capt. Jang Do-young said during a regular press briefing.

Jang urged the public to be cautious when near inter-Korean rivers and to report any suspected landmine to police or a nearby military unit.

The alert comes days after South Korean authorities issued a flood warning for the Imjin River following heavy downpours and North Korea’s release of water from a dam without advance notice.

Seoul’s Ministry of Climate, Energy and Environment said Monday that satellite imagery confirmed water had been released from North Korea’s Hwanggang Dam on the upper reaches of the Imjin River.

A Unification Ministry official on Tuesday said joint responses to natural disasters should be treated as humanitarian matters.

“Responsible cooperation between the two sides is necessary,” the official told reporters.

An unannounced discharge from Hwanggang Dam in September 2009 caused flooding that killed six South Koreans. The following month, North Korea agreed to provide advance notice before future releases. Pyongyang sent notifications on a handful of occasions in 2010 and 2013 but has not done so since.

North Korea released water from the dam several times during last year’s monsoon season, prompting the Unification Ministry to publicly urge Pyongyang to provide advance notice. A ministry spokeswoman said the appeal served as a form of “indirect communication” because Pyongyang had cut off inter-Korean communication channels in April 2023.

Thursday’s warning also comes as Pyongyang continues an extended campaign to fortify the border and harden its military posture toward South Korea, including laying large numbers of landmines inside the DMZ.

North Korean leader Kim Jong Un declared the South a “hostile state” and scrapped an inter-Korean military agreement in late 2023.

Beginning in April 2024, Pyongyang ramped up activity along the DMZ by clearing land, laying mines, reinforcing tactical roads and installing anti-tank barriers near the Military Demarcation Line.

South Korean military officials have said North Korea increased the number of troops assigned to the work from roughly 1,000 last year to about 5,000 this year.

Seoul’s Defense Ministry last month described the activity as a violation of the armistice agreement that halted fighting in the 1950-53 Korean War, an assessment later contradicted by the U.S.-led United Nations Command.