President Yoon Suk-yeol speaks during a Cabinet meeting at the presidential office in Seoul, Dec. 27. Yonhap

President Yoon Suk-yeol vowed Tuesday to strengthen the military's surveillance and reconnaissance capabilities after five North Korean drones infiltrated South Korean airspace the previous day.

Yoon said during a Cabinet meeting that Monday's incident showed clearly that the military's readiness posture and training had been "greatly lacking" and in need of strengthening.

"I believe the people clearly saw the danger of a North Korea policy that relied on North Korea's good intentions and military agreements," he said.

"We had been planning to establish a drone unit to carry out surveillance and reconnaissance operations on North Korea's key military facilities, but in the wake of yesterday's incident, we will move up the drone unit's establishment as much as possible," he added.