South Korea’s opposition moved to impeach President Yoon Suk Yeol on Wednesday after his extraordinary but short-lived imposition of martial law that brought thousands of protesters to the streets.

Yoon’s shock bid to suspend civilian rule for the first time in over four decades — before being overturned by lawmakers in a night of drama — plunged South Korea into deep turmoil and alarmed its close allies.

The future of Yoon, a conservative politician and former star public prosecutor who was elected president in 2022, is now highly uncertain.

South Korea’s opposition parties — whose lawmakers jumped fences and tussled with security forces to vote down the law — filed a motion today to impeach Yoon.

“We’ve submitted an impeachment motion prepared urgently,” said Kim Yong-min from the opposition Democratic Party (DP).

They were yet to decide when to put it to a vote, but it could come as soon as Friday.

The opposition holds a large majority in the 300-member parliament and needs only a handful of defections from the president’s party to secure the two-thirds majority needed to pass the motion.

Earlier, the DP said it would file charges of “insurrection” against Yoon, his defence and interior ministers and “key military and police figures involved, such as the martial law commander and the police chief”, the DP said in a statement.

The nation’s largest umbrella labour union called an “indefinite general strike” until Yoon resigns.

Even the leader of Yoon’s own ruling party described the attempt as “tragic” while calling for those involved to be held accountable.

Meanwhile, thousands of protesters marched on President Yoon’s office in the South Korean capital in the evening.

Live feed video showed thousands of protesters marching towards Yoon’s office in central Seoul after staging a rally in Gwanghwamun Square.

Defiance

In his late-night television announcement, Yoon declared martial law, citing the threat of North Korea and “anti-state forces”.

More than 280 troops backed by 24 helicopters arrived at parliament to lock down the site. But 190 lawmakers defied rifle-carrying soldiers to force their way into parliament to vote against the move.

This left Yoon with no choice but to retract his decision and call off the military in another television address at around 4:30am (7:30pm GMT Tuesday).

Under the constitution, martial law must be lifted when a majority in parliament demands it.

Senior aides working for Yoon offered on Wednesday to resign en masse over the martial law declaration. By mid-afternoon, Yoon had yet to reappear publicly.

‘Impeachment’

The U-turn prompted jubilation among flag-waving protesters outside parliament who had braved freezing temperatures to keep vigil through the night in defiance of Yoon’s martial law order.

Lim Myeong-pan, 55, told AFP that Yoon now has to go.

“Yoon’s act of imposing it in the first place without legitimate cause is a serious crime in itself,” Lim told AFP. “He has paved his own path to impeachment with this.”

With more protests expected through Wednesday, large numbers of police were patrolling key avenues on Wednesday afternoon.

“I was so incensed I couldn’t sleep a wink last night, I came out to make sure we push out Yoon once and for all,” 50-year-old Kim Min-ho told AFP at a fresh demonstration at the assembly Wednesday.

‘Anti-state’ elements

Yoon had said that his imposition of martial law was to “safeguard a liberal South Korea from the threats posed by North Korea’s communist forces and to eliminate anti-state elements plundering people’s freedom and happiness”.

Yoon did not elaborate on the North’s threats, but the South remains technically at war with nuclear-armed Pyongyang.

“Our National Assembly has become a haven for criminals, a den of legislative dictatorship that seeks to paralyse the judicial and administrative systems and overturn our liberal democratic order,” Yoon said.

The president labelled the main opposition Democratic Party “anti-state forces intent on overthrowing the regime”.

In recent weeks Yoon and his People Power Party have been bitterly at odds with the opposition over next year’s budget.

Opposition MPs last week approved a budget plan through a parliamentary committee that slashed Yoon’s spending plans.

His approval rating dropped to 19 per cent in the latest Gallup poll last week, with voters angry at the state of the economy as well as controversies involving his wife, Kim Keon Hee.

Concern, relief

Democratic South Korea is a major ally of the United States, which has nearly 30,000 troops in the country to protect it from the nuclear-armed North.

Washington said it had no prior notice of Yoon’s plan to impose martial law and welcomed his decision to reverse his move.

“We continue to expect political disagreements to be resolved peacefully and in accordance with the rule of law,” US Secretary of State Antony Blinken said.

China, a key ally of North Korea, urged its nationals in the South to stay calm and exercise caution, while Japan was monitoring the situation with “exceptional and serious concerns”.

“This is a surprising last-ditch move by Yoon to grab political power,” Gi-Wook Shin, a sociology professor at Stanford University, told AFP.

“This move will only fasten the demise of his political career as it is likely to lead to his impeachment. “

Reactions to martial law bid

China

China has expressed hope that South Korea will take effective measures to ensure the safety of Chinese citizens and institutions, its foreign ministry said.

The comments were made in response to a question about South Korea’s brief imposition of martial law and its potential impact on China-South Korea relations and the security situation on the Korean Peninsula.

China’s position on the Korean Peninsula issue remains unchanged, the ministry said in a statement.

“Regarding South Korea’s internal affairs, China will not comment … We hope South Korea takes effective measures to ensure the safety of Chinese citizens and institutions there,” foreign ministry spokesman Lin Jian said in a written answer to questions posed by journalists.

Russia

Russia is following events in South Korea with concern after the president briefly declared martial law, but there are no threats to Russian citizens there, Foreign Ministry spokeswoman Maria Zakharova has said.

Moscow has deepened ties with Seoul’s neighbour North Korea since the start of its war in Ukraine, drawing concern from Western countries.

“We are watching with concern the tragic events unfolding in South Korea,” Zakharova told a news briefing. “The situation on the Korean peninsula is already complicated by the provocative actions of the United States of America and its allies,” she said.

Japan

Japanese Prime Minister Shigeru Ishiba said that Tokyo was monitoring the situation in South Korea with “exceptional and serious concerns” after the Asian neighbour’s president declared then revoked martial law overnight.

Ishiba also said Tokyo was unaware of “any information suggesting that Japanese citizens [living in South Korea] were injured”.

Speaking to reporters at his office, Ishiba added the government was “taking all possible measures” to ensure the safety of Japanese nationals, including issuing warnings through consular emails. “We will continue to do everything we can to ensure their safety,” he said.

Japanese defence minister Gen Nakatani has decided to postpone a visit to South Korea, which was tentatively planned for later this month, Kyodo news agency reported, citing unnamed sources.

Nato

Nato chief Mark Rutte welcomed the swift reversal by South Korean lawmakers of President Yoon Suk Yeol’s shock imposition of martial law as proof of the country’s commitment to the rule of law.

“I think that the announcement of the end of martial law indicates South Korea’s ongoing commitment to the rule of law,” Rutte told reporters, adding “We continue to monitor the developments” in the Nato partner country.