Why South Korea’s president Yoon declared and then lifted martial law

South Korea's President Yoon Suk Yeol declared martial law without warning in a speech late Tuesday night, setting off six hours of political turmoil in the democratic Asian nation that ended only when parliament forced him to back down.

His dramatic decree, which sought to suspend political activities and impose military control, crumbled in the face of crowded opposition from lawmakers across party lines.

President Yoon, who has held office since 2022, justified his decree by accusing political opponents of "anti-state activities plotting rebellion" and alleging they were "pro-North Korean forces."

However, the decision takes place against the backdrop of months of intense political conflict between South Korea’s leader and the opposition-controlled National Assembly.

While corruption scandals involving him and his wife, Yoon pointed to repeated efforts by his rivals to impeach key figures in his administration and their blocking of budget legislation as reasons supporting his justification of martial law.

The martial law declaration empowered Army Chief of Staff General Park An-su as martial law commander.

The military decree banned all political activities, including those of the National Assembly and regional assemblies. It also imposed restrictions on press freedom and ordered striking medical workers to return to work within 48 hours.

The president's move faced immediate resistance, with 190 legislators from the 300-person National Assembly entering the chamber despite a heavy military presence—far exceeding the 150 required for a vote. By around 1 a.m., they unanimously rejected the president's order.

During the tense and shocking hours under martial law, heavily armed special operations forces surrounded the parliament, backed by army helicopters and armoured vehicles.

Lawmakers climbed walls to get into the building and held off troops by activating fire extinguishers.

Politician and former news anchor Ahn Gwi-ryeong tried to pull away an assault rifle a soldier had pointed at her chest as she shouted: “Aren’t you ashamed of yourselves?”.

Lawmakers on both sides opposed martial law. The opposition lambasted Yoon's actions as undemocratic. Opposition leader Lee Jae-myung, who narrowly lost to Yoon in the 2022 presidential election, called Yoon’s announcement “illegal and unconstitutional.”

The sudden declaration was also opposed by the leader of Yoon's own conservative party, Han Dong-hoon, who called the decision wrong and vowed to “stop it with the people.”

“The people will block the president’s anti-constitutional step. The military must be on the side of the public in any case. Let’s resolutely oppose it,” Kim Dong Yeon, the opposition party governor of Gyeonggi province, which surrounds Seoul, wrote on X.

Average South Koreans were in shock. Social media was flooded with messages expressing surprise and worry over Yoon’s announcement.

Political struggle

There were quick claims that the emergency declaration was linked to Yoon’s political struggles.

Yoon, a career prosecutor, squeezed out a victory in the tightest presidential election in South Korean history in 2022. He rode a wave of discontent over economic policy, scandals and gender wars, aiming to reshape the political future of Asia's fourth-largest economy.

But he has been unpopular, with his support ratings hovering at around 20 percent for months.

His People Power Party suffered a landslide defeat at a parliamentary election in April this year, ceding control of the unicameral assembly to opposition parties that captured nearly two-thirds of the seats.

Just this month, Yoon denied wrongdoing in an influence-peddling scandal involving him and his wife.

The scandal centres on claims that Yoon and first lady Kim Keon Hee exerted inappropriate influence on the conservative ruling People Power Party to pick a certain candidate to run for a parliamentary by-election in 2022 at the request of Myung Tae-kyun, an election broker and founder of a polling agency who conducted free opinion surveys for Yoon before he became president.

Martial law is extremely sensitive in South Korea.

South Korea became a democracy only in the late 1980s, and military intervention in civilian affairs is still a touchy subject.

There have been more than a dozen instances of martial law being declared since South Korea was established as a republic in 1948.

The declaration stirred memories of South Korea's last martial law in 1980 when military forces led by Chun Dohwan forced then-President Choi Kyu-hah to proclaim martial law and violently suppressed pro-democracy protests in Gwangju, resulting in about 200 deaths.

Allies concerned

The crisis in a country that has been a democracy for thirty-seven years, and is a US ally and major Asian economy, caused international alarm.

US officials expressed “grave concern” over the martial law declaration, emphasizing the potential instability it could bring to a region already fraught with geopolitical tensions​.

The White House said it was pleased Yoon had backed down.

“We are relieved President Yoon has reversed course on his concerning declaration of martial law and respected the... National Assembly’s vote to end it," a White House spokesperson said.

The declaration also harmed the economy by hitting South Korean won currency, which came off a more than two-year low against the dollar after Yoon's reversal, while exchange-traded funds linked to South Korean stocks similarly cut losses.

The political uncertainty also rattled investors, with stock-linked exchange-traded funds experiencing significant volatility​.