Military authorities are reportedly investigating the circumstances in which personal data on overseas South Korean agents was handed over to the North.

About a month ago, the Defense Counterintelligence Command found a leak of classified personal information on overseas agents belonging to the Korea Defense Intelligence Command.

The leaked data is said to concern not only agents acting publicly as diplomats stationed at embassies but also undercover agents doing spy work with their identities concealed.

Military authorities have discovered that many of the agents affected by the leak were tasked with operations related to North Korea, and officials have detected signs the leaked data was directed to the North.

If this is true, it is a matter of great concern. If the hidden identities of undercover agents had been revealed, not only their lives but also those North Koreans who provided information to South Korea could be in danger. Overseas undercover agents of the Defense Intelligence Command disguise themselves and contact North Korean figures.

The Defense Counterintelligence Command is said to have stopped the activities of some undercover agents and rushed them home.

Once the identities of agents are disclosed, it becomes impossible to keep them on the same missions. A hasty recall of overseas undercover agents means that human intelligence networks they have struggled to build are at risk of crumbling. Once they are broken up, it is practically impossible to restore them and it takes a long time to rebuild new networks. The leak of data on agents is a terrible blow to South Korea's intelligence and counterintelligence systems.

Military authorities must clarify the whole story of the incident, including what channels were used to leak data to North Korea, and draw up strong measures to prevent a recurrence.

The Defense Counterintelligence Command reportedly found circumstances in which data moved from internal computers of the Korea Defense Intelligence Command to the personal laptop of an employee of the command, and then data stored in the laptop was leaked externally.

It is impossible to hack into the intranet of the command because it is physically separated from the internet. Considering this, military authorities are investigating whether there were internal accomplices or helpers. To begin with, classified data on agents should not have been stored in a laptop that can be taken out of the command. Authorities must grasp why and how classified data came to be stored on the laptop in the first place. The possibility of the employee being turned by North Korea should not be excluded.

This is not the first time secrets have been leaked from the intelligence command. In 2018, an officer of the command was caught selling the identities and other information of its China-based undercover agents. At that time, the command perceived the leak too late -- about five years after the crime began.

In 2017, the Defense Integrated Data Center was hacked and about 15 million pages of classified information, including an operation plan to incapacitate the North Korean military leadership and US-provided intelligence on North Korea, was leaked to North Korea. But the then Defense Minister said, "Don't worry too much." This happened under the Moon Jae-in administration. Human intelligence networks were weakened under Moon.

The Yoon Suk Yeol administration has made efforts to strengthen the ability to collect intelligence through human networks. But if data on agents has been leaked, such efforts will go down the drain.

The crisis on the Korean Peninsula has been escalating over North Korea's continuous upgrade of its nuclear weapons programs. It has also strengthened military relations with Russia. Collapse of intelligence networks in this precarious situation could inflict irreparable damage to the country's security.

Military authorities must check their intelligence systems for loopholes and close them. To prevent a relapse, they have to tighten military discipline and arouse caution on the importance of intelligence and security. The survival of the nation is at stake.