A suspicious man spotted inside a base of the Navy’s 2nd Fleet Command in Pyeongtaek, Gyeonggi Province, turned out to be one of its soldiers.

Fortunately, the command had not been infiltrated. But the incident revealed a deplorable lack of military discipline.

The Ministry of National Defense said Saturday the unidentified man detected near an ammunition depot inside the command was found to be a petty officer third class, who was on duty at a nearby sentry post.

The soldier went AWOL from his guard post at about 10 p.m. on July 4 to buy drinks from a vending machine in an enlisted soldiers quarters about 200 meters from his post. He left his rifle behind.

On the way back to his post, he was spotted by soldiers standing guard at the ammunition depot, then ran away without responding when asked for a countersign. It is hardly imaginable for a soldier on duty to do something so ridiculous. And the developments that followed are jaw-dropping.

The entire command was alerted and searched the base only to find no traces of infiltration. Investigators then suspected someone inside the base as the suspicious figure.

On the following day, a commissioned officer gathered a group of soldiers and proposed one of them surrender. A petty officer second class slated to be discharged next month surrendered. But investigations by military police found his surrender to be false. Whether the officer coerced a false surrender should be investigated.

The petty officer third class did not allegedly surrender for fear of being punished. To put it in a nutshell, a soldier deserted his sentry box and his commanding officer tried to manipulate the situation without trying to find out the truth.

The AWOL, cover-up and imputation of responsibility are far from what we should expect from the military. Thorough investigations are needed and those responsible should be strictly punished.

Without revelations by Rep. Kim Joong-ro of the Bareunmirae Party, the false surrender and confession would not have become known to the public.

Top military officers received reports on the detection of a suspicious person inside the naval base, but they did not know of the cover-up and manipulation attempt until Kim revealed it.

Whether the report of the attempt was intentionally omitted or procrastinated upon must be investigated.

This incident came less than a month after four North Koreans entered South Korean seas on a small wooden boat and anchored it at Samcheok Port on June 15, moving unnoticed all along.

The failure to detect the boat astonished the nation, and cover-up attempts fanned distrust of the military. The defense minister apologized and urged the entire military to keep perfect guard. But little has changed in its lax military discipline.

The armed forces failed to detect another unmanned North Korean wooden boat until it came within about 30 meters of the coast near Goseong, Gangwon Province, Friday. The boat was first found by police.

A commander of an Air Force unit is under investigation on suspicions that he sent a pilot on emergency standby on an errand to fly a helicopter to bring e-cigarettes to one of his acquaintances. Five enlisted soldiers of an Army unit in Gyeonggi Province are being investigated for gambling illegally with their personal cellphones.

Holes in vigilance are concerning, and it is dispiriting that the military has not broken the habit of cover-ups and manipulation. The military must tighten discipline to prevent public concerns over lax vigilance and national security. It ought to find truth through a thorough investigation and deal with those involved, accordingly.

Soldiers must be mentally armed at all times to capture infiltrators. Yet the South Korean military appears anxious to avoid offending its enemy. Top officers say the country can be defended by dialogue, not by strength. Lax vigilance, underreporting and cover-ups are the consequences of such a mental state.

Military discipline must never be slack, even when inter-Korean ties are improving. Without a strong defense, peace is built on sand.