South Korean President Yoon Suk Yeol is facing pressure to step down after his martial law announcement shocked MPs, the public and international allies.
An impeachment hearing is now looming over Mr Yoon after the move backfired, leading to huge protests and MPs blocking the martial law declaration.
But how did things escalate so quickly – and what now?
President declares martial law
Mr Yoon declared martial law in a TV address on Tuesday, giving the military commander unlimited authority to make and enforce laws.
Martial law suspends all existing laws – meaning there can be a suspension of normal civil rights and the use of military law on the civilian population.
The step is taken when the civilian authorities are deemed unable to function, and is usually only invoked in times of war, rebellion or natural disaster.
The surprise move was the first declaration of martial law since the country’s democratisation in 1987.
Why did the president introduce it?
Mr Yoon told the nation that martial law was needed to defend the country from nuclear-armed North Korea and pro-North anti-state forces, and protect its free constitutional order, although he cited no specific threats.
But security and defence analyst Professor Michael Clarke told Sky News he believed the introduction of martial law was simply Mr Yoon’s attempt to thwart his political opponents.
South Korea protests: Follow live updates
The move came after two years of Mr Yoon struggling to push his agendas through in an opposition-controlled parliament.
His conservative People Power Party has been in a deadlock with the liberal Democratic Party over next year’s budget bill, and the president has also dismissed calls for independent investigations into scandals involving his wife and top officials, drawing criticism from his political rivals.
Mass protests erupt while MPs vote
Opposition leader Lee Jae-myung said the declaration of martial law was “unconstitutional” and called for the public to protest outside parliament in South Korean capital, Seoul.
Even some members of the president’s own party, including its leader Han Dong-hoon, spoke out against him.
Huge crowds clashed with police officers and soldiers trying to enforce martial law outside the National Assembly on Tuesday.
South Korean martial law soldiers try to enter the National Assembly on Tuesday: Newsis/AP
Parliament staff set up a barricade to block soldiers. Pic: Reuters
Some protesters were seen blocking military vehicles from moving, while military helicopters were seen flying above.
Mr Yoon had ordered in his declaration that all political party and parliamentary activities cease, but MPs still headed to parliament to vote on the martial law ruling.
As clashes continued outside, MPs voted to block the declaration.
Confusion until president accepts vote
Once the vote went through, the speaker in parliament said the president’s martial law declaration was invalid.
Opposition leader Lee Jae-myung spoke afterwards, saying anyone acting under the orders of Mr Yoon’s martial law command was “breaking the law”.
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South Korea’s opposition leader responds
But the president hadn’t commented yet and Lee Jae-myung said his party’s MPs would remain inside parliament until Mr Yoon formally lifted the order.
Protesters stayed outside parliament long into the night, putting troops and police in a challenging position. Small scuffles between them and protesters were seen continuing even after the vote.
Hours after the vote, and after his own party urged him to lift martial law, the president, in a national address, said: “I have accepted the decision made by the National Assembly to dissolve and lift the martial law.”
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South Korean president lifts martial law order
What is happening now?
Opposition politicians in South Korea have put forward a motion to impeach President Yoon Suk Yeol over his attempt to impose martial law.
The motion will need to be debated before going to a vote, which is possible on Friday, Democratic Party politician Kim Yong-min said.
Asia correspondent Nicole Johnston says things have been “a little calmer on the street” in Seoul today compared with “those crazy scenes that we had deep into the night last night”.
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Impeachment protests in Seoul
But thousands of people have attended a candlelit rally in the capital, with many protesters displaying signs calling for the president’s resignation.
“This is a country with a rich history of protest, and it’s been swift in this particular moment,” says Asia correspondent Cordelia Lynch, who is in Seoul.
“You’ve got a lot of people gathered here that are willing to stand up to get their voices heard – and they are now on the march.”
How does the impeachment process work?
More than two-thirds of the 300 members in the National Assembly will need to vote in favour of the impeachment for it to pass.
If it is approved, a trial will be held in front of the nine-member Constitutional Court. Six of those members will need to vote in favour to sustain the impeachment.
If the impeachment passes, Yoon will be stripped of his constitutional powers and removed from office.
Han Duck-soo, the South Korean prime minister, would take over his presidential responsibilities as the second in command in the government.
The whole process could take months, according to Nicole Johnston, who believes the president may decide that stepping down is his best option.