A recent string of defections by North Korean soldiers across the inter-Korean border, as intelligence sources here suggest, may point to crumbling discipline within the key apparatus shoring up the impoverished regime.

A 17-year-old soldier crossed the Military Demarcation Line near the truce village of Panmunjeom on Saturday after shooting two superiors dead. Four days earlier, another soldier defected to the South on the eastern front. A third North Korean soldier crossed the heavily-armed land border in August, waving a white flag.

The defections appear to reflect growing disgruntlement and slackening discipline in the North Korean army, which has buttressed the failing regime. The North selects its front-line troops from soldiers with relatively good family backgrounds out of concern that they may flee to the South. Soldiers deployed in Panmunjeom and nearby places, in particular, are believed to have passed tough screening.

The shock Pyongyang might have felt at Saturday’s bloody defection was mirrored in the order North Korean leader Kim Jong-un made to the Public Security Ministry the following day to “sternly crush the enemy’s ideological and cultural infiltration.” Top North Korean military and party officials were spotted on the same day inspecting the post near Panmunjeom where the defecting soldier had stood guard.

Kim might have been more shocked by the young soldier’s defection after killing his platoon and squad commanders than the failure of last April’s test-firing of a ballistic missile under the pretext of a satellite launch. Since he took over in December following the death of his father Kim Jong-il, the North Korean military has been allotted less supplies, and plagued with beatings and other physical abuse, according to intelligence sources here.

He may be turning to a more oppressive rule to strengthen discipline in the Army and tighten his grip on the regime, which he had seemed to be easing somewhat in recent months with his emphasis on the livelihoods of his people. A North Korean civilian defector, who was caught last month on the western border island of Gyodong, told South Korean interrogators that he had passed through several checkpoints without being stopped on his long defection route from a village far north.

As some North Korea watchers here note, there is a concern that Kim may seek to heighten tensions with the South through provocative acts in order to toughen up his reign. Recent incursions of North Korean fishing vessels into South Korean waters near the disputed maritime border in the West Sea have already prompted speculation that he may attempt to influence the outcome of the Dec. 19 presidential election in the South by making provocations in a measured way.

What should worry us equally or more is the lax border security of the South Korean Army revealed by the latest defection cases. South Korean border guards had failed to stop the North Korean soldier defecting on the eastern front early last week until he approached their barracks after passing through two posts and barbed wire between them. The front-line unit would have suffered grave casualties if armed North Korean troops had infiltrated like that with intent to attack.

The South Korean military proved to have concealed the case until it was disclosed by an opposition lawmaker during the parliamentary inspection of the Joint Chiefs of Staff on Monday. To its further embarrassment, the lawmaker also revealed that the North Korean civilian defector had been put in military custody five days after reaching the western island. A resident found him asleep in a deserted house and reported the discovery to a nearby marine unit.

JCS Chairman Gen. Jung Seung-jo admitted that there had been grave loopholes in its vigilance, saying thorough scrutiny was under way to check the duty of guard along the front line.

The loose military posture is worrisome particularly at a time when it should be on higher alert during a period of power transition here. Discipline should be strengthened for soldiers and other measures including installing more sophisticated surveillance equipment should be taken to tighten the border guard.

All three major presidential candidates have suggested they would seek to resume dialogue with Pyongyang if elected. Even in that case, the military would have to remain more vigilant to help induce the North to be more serious toward inter-Korean talks and less tempted into intimidating the South to draw concessions.