On the first day of 2022, South Korea’s eastern front-line fence was breached -- again.

A person presumed to be a civilian crossed the heavily guarded Military Demarcation Line into North Korea at around 10:40 p.m. on Saturday, according to the Joint Chiefs of Staff. At around 9:20 p.m., the military spotted the unidentified person in the Demilitarized Zone separating the two Koreas. Troops searched but failed to capture the DMZ trespasser.

In a fact-finding process later, authorities found that at around 6:40 p.m., a surveillance camera caught the person breaking through the barbed-wire fence to trespass in the DMZ. The military learned of the DMZ infiltration two hours and 40 minutes later. The soldier in charge of monitoring CCTV footage is said to have missed the person breaching the barbed-wire fence.

A motion sensor at the fence sounded an alarm, so an initial response team rushed to the scene, but it found nothing unusual. The unit reported “all clear” and withdrew.

Surveillance equipment captured the trespasser doubly --- by camera and sensor alarm -- but the military lost the opportunities. The fundamental military mission of surveillance failed.

The trespasser was detected at around 9:20 p.m. in images captured by a thermal observation device in the DMZ. Then the footage was played back and it showed the person breaching the DMZ fence. A search operation was launched, but it was too late.

In February last year, a North Korean swam south across the Military Demarcation Line then walked along the South Korean coast, undetected all along by a sentry of the 22nd Division. Surveillance systems sounded alarms on two occasions, but they were ignored.

After the incident, Defense Minister Suh Wook vowed to examine surveillance problems of the unit closely. Two months later, Suh presided over a meeting on defense reforms where he said he would upgrade the scientific guard system of the division with artificial intelligence. Eight months later, however, the unit’s surveillance system was breached again.

The equipment was not the problem. Human error was. Cameras, motion sensors and thermal observation devices captured the trespasser, while the military first perceived “something unusual” nearly three hours after the DMZ fence breach. Equipment becomes useless no matter how high-tech it is if human operators do not use it properly.

The camera captured the DMZ trespasser at 6:40 p.m. It was neither late night nor dawn. Even the sensor on the fence sounded an alarm. They worked mechanically. The initial response team should have searched for traces at the scene more carefully. It is questionable if they searched perfunctorily.

When a North Korean breached a barbed-wire fence in Gangwon Province for defection to the South in November 2020, the surveillance sensor system did not work. In July of that year, military surveillance equipment captured a South Korean crossing the Han River into North Korea, but the military had no idea until the North announced the defection.

In 2019, a small unmotorized wooden boat with four North Koreans aboard arrived at the port of Samcheok, Gangwon Province, for defection after crossing the inter-Korean maritime border unchecked.

The ministry announced sweeping measures, including a budget to upgrade the scientific guard system, but the front-line surveillance situation has not improved at all. If the work discipline of sentry soldiers is not reinforced, recurrences of similar incidents will be unavoidable.

Suh inspected combat readiness aboard an aircraft during its 140-minute patrol mission on Jan. 1, according to the Defense Ministry. He talked by phone with seven battalion commanders in charge of ground observation posts in front-line areas. He told them that the South Korean military, with a potent force, supported efforts to settle an everlasting peace on the Korean Peninsula. Hours later the front line was breached with a person going to North Korea.

Suh and other military leaders should reflect on whether the military discipline of guards has crumbled while they emphasize “peace” rather than training.