Five North Korean drones crossed into South Korea on Monday, prompting South Korea’s military to scramble fighter jets and attack helicopters, though it failed to bring down the drones, which flew over South Korea for hours.

Amid criticism over South Korea’s air defences at a time of North Korea’s growing nuclear and missile threats, Yoon visited the state-run Agency for Defence Development to check the country’s reconnaissance and interception capabilities and called for an overhaul of the response system against “all flying objects.”

“North Korea’s drone intrusion of our airspace is an intolerable incident,” Yoon said.

“We should let them learn that provocations are always met by harsh consequences.”

Yoon has slammed the military’s handling of Monday’s incursion, the first since 2017, urging it to hasten the reinforcement of drone units.

The military apologised for its response, and said it could not shoot down the drones because they were too small.

“To secure peace, we need to prepare for a war with overwhelming capabilities,” the president said, adding that the South’s defence procurement strategy should also be reviewed in line with the North’s weapons advances.

On Thursday, the South’s Joint Chiefs of Staff said the country’s military will hold drone-focused exercises.

“Our military will conduct joint air defence drills to simulate responses to small-sized unmanned enemy aircraft,” a JCS spokesman told a regular briefing.