Five soldiers were killed and seven others wounded in a shooting spree that took place at a front-line Army unit in Goseong, a town on the east coast, on Saturday evening.

The perpetrator was an Army sergeant surnamed Lim, who had only three months left before the end of his military service. The motive for the shootings is yet to be known.

A Defense Ministry official said Lim opened fire on his comrades after doing his six-hour sentry duty at a general outpost near the inter-Korean border. Before going on a rampage, he detonated a grenade, but there were no casualties from the detonation.

After the killing spree, the shooter escaped with a grenade, a gun and some 60 rounds of ammunition. The next day, he had a shootout with soldiers chasing him near a roadside checkpoint some 10 kilometers from his post. One officer was wounded in the shootout.

The tragic shooting has raised several questions. First of all, Lim was found to be on the list of soldiers who required special attention due to difficulties in adapting to life in the barracks.

“Attention-requiring” soldiers are not qualified for sentry duty at front-line outposts. As soldiers at outposts live in isolation, those bullied by their comrades often have no one to look to for help. Lacking self-control, they can easily blow up under stress.

Then why was Lim assigned to guard duty? The Defense Ministry says it classifies soldiers requiring special attention into three groups and excludes only those with an “A” rating from guard duty at front-line outposts.

Lim was first given an “A” rating in April last year but received a “B” rating after a second test in November. So he began to perform guard duty in December.

The ministry says that due to a personnel shortage, it is inevitable for front-line units to assign attention-requiring soldiers to guard duty at outposts. On average, it says, such soldiers account for about 20 percent of Army troops.

If it is inevitable to assign soldiers requiring special attention to stressful tasks due to troop shortages, the ministry needs to arrange for them to be taken care of by their superiors or comrades.

The killing spree in Goseong is not the first committed by a soldier. In 2011, a Marine corporal went on a rampage at his unit on Ganghwado Island, killing four comrades and wounding one.

In 2005, an Army private killed eight colleagues and wounded two others at a front-line border unit.

Fatal firearm accidents in the barracks should be prevented by all means. Otherwise, parents cannot rest assured that their sons are safe while serving in the military.