The South Korean president's top advisor vowed on Wednesday to punish whoever is found responsible for a recent drone incursion into North Korea, after a furious Pyongyang demanded an apology.
North Korea accused the South over the weekend of sending a drone across their shared border into the city of Kaesong this month, releasing photos of debris from what it said was the downed aircraft.
And on Tuesday the North Korean leader's powerful sister, Kim Yo Jong, demanded an apology over the incident from the "hooligans of the enemy state" responsible.
Seoul has denied any involvement but has left open the possibility that civilians may have flown the drone, a position reiterated by National Security Adviser Wi Sung-lac on Wednesday.
"Our understanding so far is that neither the military nor the government carried out such an operation," Wi told reporters on the sidelines of a summit between the leaders of South Korea and Japan in the Japanese city of Nara.
"That leaves us the task to investigate if someone from the civilian sector may have done it," he said.
"If there is anything that warrants punishment, then there should be punishment."
South and North Korea remain technically at war, as the 1950-53 Korean War ended with an armistice rather than a peace treaty.
Wi noted that despite Pyongyang's criticism and its demand for an apology, the North has also sent its own drones into South Korea.
"There have been incidents in which their drones fell near the Blue House, and others that reached Yongsan," he said, referring to the current and former locations of the presidential offices.
"These, too, are violations of the Armistice Agreement," he said.
South Korean President Lee Jae Myung has ordered a joint military-police probe into the drone case.
Any civilian involvement would be "a serious crime that threatens peace on the Korean peninsula", he warned.
