The soldier who went on a rampage at his DMZ guard post in Gangwon-do has been caught—alive, no less—but the story is by no means over.

The Ministry of Defense is saying there are a lot of potential problem soldiers in the military. How many, you might ask? This many:

Speaking at a June 23 morning briefing on a recent incident in which a soldier identified by his surname Lim fatally shot five colleagues, ministry spokesman Kim Min-seok explained, “The 22nd Infantry Division [where Lim worked] has around 1,800 troops listed as ‘requiring special attention’ in the three categories of A, B, and C, or about 20% of all troops.”

Kim went on to say, “They’re not all clustered in the 22nd Division. There’s just generally a lot of soldiers that require attention.”

When asked by a reporter if the issue extended throughout the military, Kim said, “I believe the rate is similar [around 20%] for the military as a whole.”

Lim was one such soldier:

According to the Army, Lim enlisted in December 2012 after his freshman year in college and was assigned to the 22nd division in February 2013.

However, he was sidelined from performing patrols at the border in April last year following the outcome of a military-conducted personality test, which showed that he required special attention.

Lim’s test results put him in the highest Level A, indicating that he needed extra supervision and was mentally unfit to perform the border patrols. Level C is for those who just joined the Army less than four months ago or are deemed too weak to perform their duties.

But just seven months later, the sergeant was downgraded to Level B, which enabled him to perform border patrol duties, a task that carries a high risk. One military official, who spoke on the condition of anonymity, said that Lim’s unit downgraded his personality assessment because he had shown improvement in his character in the time since.

The problem, both military and non-military folk say, is that the army’s chronic manpower shortages—which won’t be getting any better—make it necessary to put “soldiers of interest” on the DMZ for guard duty. One army captain who lead a platoon on the DMZ told Newsis that in some platoons, half the guys are “soldiers of interest.”

Meanwhile, the military response to the incident is being criticized for being something of a clusterfuck, with poor communication between the military and the police, belated orders to evacuate civilians, and a friendly fire incident in which one trooper almost got his head blown off.

As for why a guy with only three months left in the service would go postal, it appears he was just a very introverted guy who did not get along with his fellow soldiers and, on a practical level, may have been treated lower than his actual rank.

UPDATE: Great, if somewhat disconcerting, photograph from the standoff: