A Chinese national indicted on charges of entering South Korea and habitually eavesdropping on communications between South Korea-U.S. fighter jets and control towers has been revealed to be a former officer who served for 40 years in the Chinese People's Liberation Army eavesdropping unit.

According to the prosecution's indictment, the Chinese national in his 60s, surnamed A, served for 40 years in an eavesdropping unit under the General Staff Department of the People's Liberation Army in Beijing.

Investigations showed that he reached the rank of zhongxiao, which corresponds to a lieutenant colonel in the South Korean military.

After retiring, A is accused of traveling to various locations including the Gunsan, Osan, and Gwangju Air Bases in North Jeolla and Gyeonggi Provinces, Camp Humphreys in Pyeongtaek, and the Busan Naval Base from March 2024 until last month, eavesdropping on military communications a total of 13 times.

Investigations revealed that he mostly booked hotel rooms close to air bases, where he set up radio receivers and antennas to listen in on communications between fighter pilots and control towers.

Out of the 13 instances, 7 targeted Gunsan Airport, which is jointly used by the South Korean and U.S. militaries.

The prosecution believes that A saved the recorded files and frequency information necessary for eavesdropping onto external hard drives and took them back to China.

The stored data amounted to 13.9 terabytes.

A had departed for China and re-entered South Korea early last month ahead of the South Korea-U.S. joint military exercise, Freedom Shield.

Police caught A red-handed while he was eavesdropping on communications at a hotel in Gunsan, and he reportedly denied the charges, claiming it was "a hobby."

The prosecution has also found that another Chinese national, B, who was detained around the same time, has a background of serving in the People's Liberation Army special forces and China's Ministry of Public Security.

Investigations showed that B operated a military supply store near Camp Humphreys in Pyeongtaek, approaching active-duty U.S. service members and a South Korean civilian employee working in the Eighth U.S. Army commanding general's office.

The prosecution believes that B built relationships by treating them to meals and giving gifts, and subsequently received materials including training footage of Apache attack helicopters and F-35 fighter jets, data related to South Korea-U.S. joint exercises, and information regarding U.S. military leadership.

Investigations indicated that some of the collected materials were transmitted externally via Chinese messenger services.

B is also denying the charges, claiming that he merely built friendly ties with military personnel in the process of running his military supply store business.

The two individuals have been detained and indicted on charges including aiding the enemy.

(Reported by Kim Minjeong | Video by Kim Na-on | Graphics by Lee Jeong-ju | Produced by SBS Digital News)