The U.S. Department of Energy’s (DOE) designation of South Korea as a “sensitive country” has ignited domestic controversy, with a recent revelation further fueling the debate. It has emerged that two years ago, a contract employee at a DOE-affiliated research lab was caught attempting to take nuclear reactor design software to South Korea. While discussions in South Korea have largely focused on political and policy-related implications—including calls from conservative factions for nuclear armament and broader political tensions such as emergency martial law and impeachment debates involving President Yoon Suk-yeol—U.S. authorities have reportedly cited multiple security incidents involving South Korea as a key justification for the designation. South Korea has never officially declared an intention to develop nuclear weapons nor communicated such plans to the United States through diplomatic channels.
According to a report submitted to Congress in the first half of last year by the DOE’s Office of Inspector General (OIG), a contractor employee at Idaho National Laboratory (INL), a DOE-affiliated facility, was apprehended while attempting to take reactor design software to South Korea. The incident occurred between Oct. 1, 2023, and Mar. 31, 2024, and was listed as the first case in the report. The official account of the incident is detailed in the U.S. Department of OIG Semiannual Report to Congress for the period ending Mar. 31, 2024. The report states that the employee was caught at an airport attempting to board a flight to South Korea while in possession of export-controlled, proprietary reactor software owned by INL. The employee was subsequently terminated, and investigations by the Federal Bureau of Investigation (FBI) and Homeland Security Investigations (HSI) remain ongoing.
The OIG further reported that a search of the employee’s government emails and chat records revealed awareness of export control restrictions and communications with a foreign government. While the report did not specify which government was involved, the attempt to take reactor design materials to South Korea strongly suggests it was the South Korean government.
A diplomatic source familiar with the issue stated, “Following the controversy over South Korea’s designation as a sensitive country, U.S. authorities have pointed to this case, among others, as part of their concerns regarding security risks.” On Mar. 17, South Korea’s Ministry of Foreign Affairs said, “It has been determined that South Korea was included in the lowest category of the sensitive country list due to security concerns rather than diplomatic policy issues.” In response to the designation, high-level discussions are being arranged between U.S. Energy Secretary Chris Wright and South Korean Minister of Trade, Industry and Energy Ahn Duk-geun.
The sensitive country list is managed internally by the DOE’s Office of Intelligence and Counterintelligence (OCI) for reasons including national security, counterterrorism, nuclear nonproliferation, and regional stability. When asked about the issue on Mar. 10, the U.S. Department of State said it had no involvement and directed inquiries to the DOE, suggesting the designation was made independently of broader diplomatic or security policy considerations. A source familiar with the matter noted that even DOE officials overseeing South Korea-related affairs were unaware of the designation in advance.
The “other designated countries” category within the sensitive country list includes close U.S. allies such as Israel and Taiwan, both key partners in the Indo-Pacific region. The DOE has officially confirmed that South Korea has been added to its Sensitive and Other Designated Countries List, placing it in the lowest category. Despite this designation, a DOE spokesperson emphasized that there are no new restrictions on bilateral cooperation in science and technology between the two nations. The DOE also expressed its intention to continue collaborating with South Korea on mutual interests.
The Biden administration’s decision to implement the designation between December 2024 and January 2025 came at a time when nuclear armament discussions in South Korea had largely faded amid political turmoil over martial law and impeachment debates involving President Yoon. Nevertheless, opposition politicians in South Korea have condemned the designation as a diplomatic failure, linking it to past discussions on nuclear armament. Lawmaker Wi Sung-lac, a Democratic Party foreign and security expert, stated, “The U.S. likely harbored deep concerns over nuclear armament discussions in South Korea.” Kim Joon-hyung, a lawmaker from the minor progressive Rebuilding Korea Party (RKP), added, “Reckless advocacy for nuclear armament has played a key role in creating this situation.” Former Vice Foreign Minister Choi Jong-kun criticized the Yoon administration, stating, “The U.S. could not trust a government driven by the twisted ambition of pursuing independent nuclear armament.” A former senior South Korean diplomat dismissed such claims, arguing, “It is nonsensical to suggest that a democratic ally would be sanctioned simply because some politicians, scholars, or media outlets have discussed nuclear armament.”
While the Biden administration remains firmly opposed to measures exceeding extended deterrence—such as redeploying U.S. tactical nuclear weapons to the Korean Peninsula or introducing a NATO-style nuclear-sharing arrangement—debates in Washington have evolved. Under the Trump administration, some policymakers and analysts began exploring the possibility of a nuclear option for South Korea in response to North Korea’s advancing nuclear and missile capabilities. Republican Senators James Risch, ranking member of the Senate Foreign Relations Committee, and Roger Wicker, ranking member of the Senate Armed Services Committee, have both advocated for considering the redeployment of U.S. nuclear weapons to South Korea. Elbridge Colby, nominee for deputy undersecretary of defense for policy and a close aide to Vice President J.D. Vance, has also argued that “all options, including independent nuclear armament for South Korea, should be on the table to maintain military balance with China.” Additionally, the conservative think tank Heritage Foundation recently proposed deploying B61 nuclear bombs—the only known U.S. tactical nuclear weapons—to Osan and Gunsan in South Korea as a response to nuclear threats from North Korea, China, and Russia.
