On Dec. 3, in an apparent attempt at a self-coup, South Korean President Yoon Suk-yeol declared martial law. The move reflects the desperation of a leader facing plummeting popularity, mired in scandal, and under mounting pressure from South Korean elites. It was the first imposition of martial law in South Korea since the end of its military dictatorship in 1987.
Yoon’s attempt barely lasted six hours, after the National Assembly unanimously revoked his declaration. He now faces impeachment and charges of treason. But the episode, however brief, serves as a stark reminder that more than one-third of the Republic of Korea’s 76-year history was spent under military rule—spanning from 1961 to 1987—followed by an additional five years under a former Army general, albeit democratically elected. The lack of military coups since then had fostered a belief that South Korea had achieved stable civil-military relations and matured into a thriving democracy. Few could have imagined that in the 21st century, armored vehicles might once again roll into the streets of Seoul or that soldiers would try to break into at the National Assembly to arrest lawmakers.
As shocking as it may seem, martial law has always been a possibility. South Korea’s past military dictatorship looms large over the country today, causing civil-military relations to fracture and democracy to falter. This moment should serve as an opportunity for South Koreans to eliminate the remnants of this history once and for all, ensuring that such incidents cannot recur in the future.
Yoon’s imposition of martial law has its roots in South Korea’s military dictatorship. Without democratic legitimacy, the military dictators who ruled in that 26-year period relied heavily on the “collective leadership” of Army officers who paid them allegiance. After Park Chung-hee’s coup in 1961, he filled key positions within the civilian administration and foreign service with members of Hanahoe—a secretive group formed in 1963 by graduates of the Korea Military Academy (KMA), a service academy for the Army. Most notably, Chun Doo-hwan, who supported Park during the coup as an Army officer, became a civil service secretary and later chief of personnel at the Korean Central Intelligence Agency.
Following Park’s assassination in October 1979, Chun, then commander of the Defense Security Command, staged a mutiny alongside other Hanahoe members. Facing widespread public outrage, Chun and his ally Roh Tae-woo orchestrated the brutal suppression of protesters in Gwangju in May 1980, leading to the deaths of hundreds, perhaps thousands. Under Chun’s regime, Hanahoe’s influence expanded further, with its members occupying critical roles in the presidential secretariat, the ruling party, and intelligence services.
Chun suspended direct presidential elections and handpicked Roh as his successor in a planned indirect presidential election in 1987. This sparked massive protests, during which several college students were killed. Under pressure from Washington, Chun ultimately conceded and reinstated direct presidential elections. Although Roh was eventually elected in 1987, South Korea’s military dictatorship officially came to an end. That doesn’t mean, however, that the military’s influence over civilian affairs truly disappeared.
Key civilian security positions are still predominantly held by former military leaders—mostly from the Army—often transitioning directly into these roles with little to no interruption after their military service. Since the 1961 coup, South Korea has not had a single minister of national defense who has not, at some point, been a member of the military. While civilians have been better represented in vice minister roles, retired military officers still constitute the majority.
This is concerning because retired military officers often maintain close ties with their service branches and the military as a whole, raising concerns about their ability to provide impartial supervision and enforce civilian authority. It also increases the likelihood of a civilian leader mobilizing the armed forces to serve their political objectives.
Adding to the concern is the homogeneity in academic and professional backgrounds among military leaders. While the Hanahoe faction no longer exists, most senior military leaders are KMA graduates and follow similar career paths within the Army. In 2020, President Moon Jae-in appointed the first non-KMA graduate as Army chief of staff in South Korea’s history, prompting unrest within Army leadership. When like-minded individuals with long-standing ties dominate senior military roles, the risk of collusion rises significantly.
Another persistent issue is the military’s strong partisan alignment, which can undermine democratic governance. Rather than operating as a politically neutral, professional institution, the South Korean military has maintained a strong affinity with conservative factions and frequently clashes with progressive civilian leadership. While it is not uncommon for military and security establishments to lean this way, the South Korean military’s conservative ties are particularly deep. During the dictatorship, the military collaborated with former military leaders and civilian members of the ruling conservative party to suppress the democratization movement led by progressives, using anti-communism and national security as justification.
These systemic flaws in civil-military relations nearly led to the imposition of martial law in 2017. While South Korea’s Constitutional Court was deliberating whether to approve Park Geun-hye’s impeachment, Defense Minister Han Min-koo, a retired Army general and KMA graduate, ordered Cho Hyun-chun, another academy graduate commanding the Defense Security Command, to set a plan for imposing martial law to suppress protests if Park were reinstated. The plan included the deployment of hundreds of armored vehicles and more than 6,000 combat troops to key locations, including the Government Complex in Seoul, the National Assembly, and various media outlets.
In order to prevent a vote to lift martial law, as the South Korean Constitution guarantees, the document also proposed arresting politicians who violated bans on protests and assemblies. It outlined measures to surveil and suppress the media, block internet portals and social media, and take control of the National Intelligence Service. Those who violated martial law were to be tried in military tribunals. Although not implemented, the mere existence of such plans in 2017 is deeply unsettling.
Now, the same civil-military problems—quasi-military dominance in key civilian defense roles, homogeneity, and partisanship—have culminated in Yoon’s attempt at a self-coup.
All three of Yoon’s defense ministers have been Army elites from KMA. Notably, Lee Jong-sup, Yoon’s first defense minister, resigned following allegations of interfering in a military investigation into the death of a young Marine, raising concerns about his loyalty to the president over the ministry and its personnel. Shin Won-sik, Yoon’s second defense minister, was later appointed national security advisor. Shin’s academy classmate, Kim Yong-hyun—who is also Yoon’s high school senior classmate, an important relationship in Korean political culture—succeeded Shin. Kim Seon-ho, the vice minister of defense, is also a KMA graduate. It was Kim Yong-hyun who proposed imposing martial law and orchestrated its implementation. He recommended Army Chief of Staff Park An-soo, a KMA junior classmate, as martial law commander to Yoon, bypassing Joint Chiefs of Staff Chairman Kim Myung-soo, the highest-ranking active-duty officer who is from the Navy. Yoon approved the appointment. Two other KMA junior classmates of Kim Yong-hyun, Special Warfare Commander Kwak Jong-geun and Capital Defense Commander Lee Jin-woo, played critical roles in mobilizing troops during Yoon’s short-lived self-coup.
As dramatically as the self-coup failed, Kim presumably believed he could make it succeed—and that the rest of the military would be on board. Contrary to the Yoon administration’s weak excuse that martial law was merely a warning to the opposition and not intended to be maintained, the first article of the martial law proclamation—which banned all political activities, including those of the National Assembly—was clearly designed to prevent the legislature from lifting martial law and to lay the groundwork for a dictatorship. However, the failure of the coup was predicted by many from the very start, and opposition was instant and successful. So why did Kim proceed with this plan?
This phenomenon can perhaps be explained as a relic of the military dictatorship, during which a particular mindset was cultivated among army officers to suppress dissent—one that views the political opposition as pro-North communist forces that must be confronted, conflating national security with regime security. In this week’s coup attempt, Kim and his military subordinates, under the pretext of eradicating “pro-North Korean anti-state forces,” which Yoon claimed as the objective, may have believed that it was their duty to achieve this goal using the tools at their disposal.
This mindset is evident in Kim’s statements following the coup attempt. Addressing the military, he said, “We were outnumbered by the enemy,” referring to civilian protesters and opposition lawmakers. When asked by reporters about his motivations, he quoted a line from the KMA Creed of Cadets: “We choose the arduous path of justice over the complacent path of injustice.” This illustrates the grave danger of placing individuals prone to groupthink in key national defense positions, where their actions can be influenced by such distorted beliefs.
Without a doubt, Yoon’s coup attempt laid bare the South Korean military’s erosion of political neutrality and its failure to operate as a professional institution. Yoon’s imposition of martial law was illegal from the outset, as it did not meet the necessary conditions for such a declaration, such as the presence of an armed rebellion, a breakdown of law and order, or an external threat that renders civilian governance impossible. The military’s compliance with these unlawful orders exacerbates concerns over its allegiance.
Moreover, despite South Korean law explicitly prohibiting the use of armed force against the legislature under martial law, special forces attempted to seize the National Assembly to block a vote to lift it. Even after the National Assembly voted to revoke martial law—legally requiring immediate presidential compliance—military officers defied the decision, insisting on maintaining martial law until Yoon personally rescinded it. In no uncertain terms, the military was loyal to an individual leader over the nation. However, young soldiers on the ground, mostly conscripts and therefore untainted by the groupthink of Army elites, appeared to display passive resistance to what they perceived as unreasonable orders, which ultimately contributed to the passage of the resolution to lift martial law.
As South Koreans and supporters of democracy around the world anxiously watch how this situation unfolds, it is crucial to learn from what happened. This incident serves as a stark reminder that civil-military relations are never static and can regress without vigilant management. If there is a silver lining to this situation, it is that South Koreans now have an opportunity to confront the lingering legacies of military dictatorship and take definitive steps toward establishing healthy, sustainable civil-military relations. These steps should include instituting a mandatory moratorium before former military officers assume civilian defense positions and diversifying national defense leadership to prevent too much power from concentrating among Army elites with homogeneous backgrounds. Most importantly, the South Korean military should mandate the comprehensive inclusion of lessons on democratic civil-military relations in its military education curriculum so these principles will guide service members’ future decision-making.
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