The operation came to light on January 18, when hundreds of police officers, led by officers of the National Intelligence Service (NIS), conducted search raids at a number of regional offices of the Korean Confederation of Trade Unions (KCTU). Founded in the mid-1990s, the KCTU represents over 1.1 million members. Most of its membership consists of supporters of the Democratic Party of Korea (DPK), a left-of-center liberal coalition that ruled South Korea until last year. Since its establishment in 2014, the DPK has been engaged in a bitter political rivalry with the People Power Party (PPP), a conservative coalition that currently governs South Korea.

On Wednesday, four KCTU officials, all of them men, between the ages of 48 and 54, were charged with several violations of South Korea’s National Security Act, including carrying out espionage on behalf of North Korea and meeting illegally with North Korean intelligence officers. South Korean government prosecutors accuse the four of meeting several times with their alleged North Korean handlers. The alleged meetings too place during overseas trips in Vietnam and Cambodia between 2017 and 2019.

While abroad, the four alleged spies were allegedly trained and given instructions to establish what prosecutors describe as “an underground organization [operating] under the guise of legal union activities”. The four men were allegedly tasked with steering the KCTU toward actions and rhetoric that were against the United States and Japan. They were also asked to helping organize worker rallies against the policies of the PPP. In other instances, the alleged spies photographed American military installations located in South Korea.

The opposition DPK has strongly condemned the charges, calling them politically motivated and describing them as a return to the days of rightwing military rule, which South Korea experienced until 1987. The NIS remains highly controversial among left-of-center South Koreans, many of whom view it as a corrupt state entity that is politically aligned with the conservative PPP. Between 2018 and 2022, the liberal DPK government spearheaded what it described as an “anti-corruption campaign” inside the NIS. As a result of that campaign, three former NIS directors were charged with —and eventually convicted of— secretly diverting funds from the agency’s clandestine budget. The funds were eventually used to aid the re-election campaign of the then-South Korean President, Park Geun-hye. Their apparent goal was to prevent the DPK from coming to power, fearing that the left-of-center party was too close to Pyongyang. President Park also went to prison for accepting financial bribes from the NIS.