South Korea’s President Yoon Suk Yeol declared martial law. What does that mean?

South Korean President Yoon Suk Yeol speaks during the declaration of emergency martial law on December 3 in Seoul. Photo / Getty Images

When martial law was last declared in South Korea in 1980, it came after a coup that installed a military dictatorship. After pro-democracy activists, mostly university students, protested in the city of Gwangju, special forces responded violently, killing about 200 people with machine guns and clubs.

More than four decades later, South Korean President Yoon Suk Yeol has declared martial law once more, this time accusing the opposition party of engaging in “anti-state” activities in alignment with North Korea.

Shortly after Yoon made his announcement in a late-night message to the nation on Tuesday, protesters tried to enter South Korea’s National Assembly, its parliamentary building, where they clashed with police. “End martial law! End martial law!” they shouted.

Yoon’s extraordinary move shocked many South Koreans and dredged up painful memories of how military rule was used in the country before it turned to democracy in the late 1980s.

Soldiers try to enter the National Assembly building in Seoul after South Korea President Yoon Suk Yeol declared martial law. Photo / AFP

While Yoon’s decision was a shock, it was not a total surprise. Rumours had swirled in South Korean political circles for months that the president was considering imposing martial law.

Officials with Yoon’s People Power Party pushed back on the rumours publicly: In September, Yoon’s ally Han Dong-hoon publicly accused opposition Democratic Party leader Lee Jae-myung of spreading “conspiracy theories” about impending martial law.

Why did Yoon declare martial law?

Yoon, 63, has held South Korea’s top office since 2022, when he succeeded Moon Jae-in, from the left-wing Democratic Party.

Unlike Moon, who favoured dialogue with North Korea, Yoon had a conservative, hawkish background. He had risen to become the presidential candidate for the PPP after serving as prosecutor general of South Korea for two years before resigning amid disputes with the Moon government.

Yoon won the presidency in one of South Korea’s tightest election races, and he quickly became mired in numerous scandals. Combined with moves that were widely seen as unnecessary, the scandals sent his approval ratings plummeting.

People gather in front of the National Assembly in Seoul after President Yoon declared martial law in a televised speech. Photo / Getty Images

He made the sudden decision after his election to relocate the presidential office from Seoul’s historic Blue House and to move the Defence Ministry – costly changes that prompted significant security concerns, despite little public support.

The South Korean president was criticised for his government’s response to a crowd crush during Halloween in 2022 that killed 159 people in Seoul’s Itaewon district. Then there was a crisis in the medical sector, with strikes and staff shortages this year as the government tried to impose changes.

The president’s family came under scrutiny this year when hidden-camera footage of his wife accepting a pricey Dior handbag as a gift was released.

Yoon’s approval rating hit a low of 17% last month, according to the Dong-A Ilbo newspaper. Yoon’s party also suffered a crushing defeat in parliamentary elections in April. Without a parliamentary majority, Yoon was forced to veto bills and had been locked in a standoff over a budget bill that he could not veto.

What does martial law mean in South Korea?

South Korea’s constitution spells out how a president can declare martial law in Article 77, stating it should be done to “cope with a military necessity or to maintain the public safety and order by mobilization of the military forces in time of war, armed conflict or similar national emergency”.

The same article also says that martial law can be overturned by a majority vote in the National Assembly.

In his remarks this week, Yoon took aim at the National Assembly, accusing it of becoming a “monster that destroys the liberal democratic system” and saying that it had proposed 22 motions to impeach government officials during his administration.

The president said he would impose martial law to stop “shameless pro-North anti-state forces that plunder the freedom and happiness of our people”.

A military decree suspended all political activities, as well as “fake news, manipulation of public opinion and false propaganda”. It said it would place news media “under martial law control” and ordered striking medical workers to return to work within 48 hours.

The decree was signed by army General Park An-su, who was designated by Yoon as “martial law commander”.

Martial law has a long history in South Korea, which transitioned to democracy in 1987. It has been imposed 16 times since the end of World War II, most recently in 1980 after the assassination of military strongman Park Chung-hee the year before.

The 1980 martial law period is most notorious for the Gwangju Uprising and subsequent military crackdown. The incident has since been depicted in South Korean films and literature.

How can South Korea’s opposition react?

While there had been talk of martial law over recent months, some analysts argued that the country had changed and that past instances of martial law were unlikely to return.

“In a high-level democracy like South Korea, could a president realistically pursue martial law, which is tantamount to a palace coup?” Wang Son-taek, an adjunct professor at Sogang University and former journalist, wrote for the Korea Herald in September. “Simply put, it is almost impossible.”

Some allies of Yoon have condemned the move. Han, the PPP party leader who previously called talk of martial law a conspiracy theory, said the move was “wrong” and pledged to stop it.

South Korean lawmakers have since voted to overturn martial law, with the 190 present representing a majority in the 300-person National Assembly.

While South Korea’s constitution says martial law can be overturned by a parliamentary vote, military officials have said so far that martial law will remain in place until Yoon lifts it, according to local reports.