In the wake of recent revelations that South Korea appears on a U.S. Department of Energy(DOE) list of “sensitive countries,” the department has disclosed that a contractor employee was fired in 2023 or 2024 after attempting to board a flight to South Korea with nuclear reactor design software. 

According to a report to the U.S. Congress from the department’s Office of the Inspector General on Monday, the Idaho National Laboratory terminated the contractor employee sometime between October 1, 2023, and March 31 last year. 

The report said the matter concerned proprietary nuclear reactor design software owned by the laboratory.

It said the Office of the Inspector General conducted a search of the employee’s government email and chat history showing the person had knowledge of export control restrictions and had communicated with a foreign government.

The report did not specify which foreign government. 

Earlier on Monday, South Korea’s foreign ministry said the U.S. included South Korea in the least sensitive category on its “sensitive and other designated countries” list due to security concerns related to DOE-affiliated institutes, not because of diplomatic policy issues. 

The U.S. government reportedly told the ministry that South Korea’s inclusion on the list was due to violations of security regulations during South Korean researchers’ visits to Energy Department laboratories or participation in joint research projects.

The U.S. didn't mention specific breaches, but the ministry believes the instance concerning the contractor employee was one of them.