Pyongyang accused Seoul of flying a drone into Kaesong earlier this year, releasing images that purported to show debris from the downed aircraft.

South Korea initially denied government involvement, suggesting civilians may have been responsible.

But police said on Tuesday they were investigating three active-duty soldiers and one spy agency employee suspected of involvement in the case.

Search and seizure warrants have been executed “at a total of 18 locations, including the Defense Intelligence Command and the National Intelligence Service,” authorities said in a statement.

Three civilians have been charged for their alleged role in the drone scandal.

One of them has publicly claimed responsibility, saying he acted to detect radiation levels from North Korea’s Pyongsan uranium processing facility.

South Korean President Lee Jae Myung has previously said flying the drone into North Korea was akin to “firing a shot” across the border.

Disgraced ex-president Yoon Suk Yeol is currently standing trial on charges he illegally sent drones into North Korea to help create the pretext for declaring martial law in late 2024.

His attempt to overturn civilian rule failed, and Yoon was impeached and ousted from office in April last year.