South Korean President Yoon Suk Yeol declared martial law overnight, then rescinded it, after blasting the opposition as "anti-state forces" threatening the country's democracy.
The unexpected move from Mr Yoon — the first time martial law has been declared in South Korea in more than four decades — has greatly alarmed the United States and the country's other allies.
So what do we know about the decision to impose martial law, the withdrawal and what might come next?
What is martial law?
Martial law is when ordinary law is suspended and civilian decision-makers are temporarily replaced by the military, usually during times of unrest or a state of emergency.
It generally gives the military much more authority to make and enforce laws.
Article 77 of South Korea's constitution states the president may proclaim martial law when "required to cope with a military necessity or to maintain the public safety and order by mobilisation of the military forces in time of war, armed conflict or similar national emergency".
In a dramatic, late-night emergency television address to the nation, Mr Yoon announced that he was imposing martial law, accusing the opposition of paralysing the government with "anti-state activities".
A six-point decree from the new martial law commander, army chief General Park An-su, swiftly followed, banning political activities and parties, "false propaganda", strikes and "gatherings that incite social unrest".
The order also brought all media outlets under the authority of martial law and directed all medical staff, including striking doctors, to return to work within 48 hours.
However, there was no outward sign of government control of media outlets, which continued to report throughout the crisis.
Has the decision been reversed?
Just hours after he made the shock declaration, Mr Yoon said Tuesday night's martial law declaration would be lifted and troops would be withdrawn.
"There was a demand from the National Assembly to lift the state of emergency, and we have withdrawn the military that was deployed for martial law operations," the South Korean president said in a televised address.
"We will accept the National Assembly's request and lift the martial law through the cabinet meeting."
The South Korean cabinet has now approved the motion to lift martial law in the country.
What happened at South Korea's parliament?
Security forces sealed the National Assembly, helicopters landed on the roof and troops entered the building for a short time, seemingly in a bid to prevent politicians from getting inside.
But 190 did manage to enter and voted unanimously to reject Mr Yoon's declaration and call for martial law to be lifted.
Reuters reported that troops equipped with rifles, body armour and night-vision equipment faced off with staffers who opposed them with fire extinguishers.
Outside, hundreds of protesters gathered, many calling for Mr Yoon to be arrested.
Why did Mr Yoon do this?
Mr Yoon said he was acting to safeguard his country's liberal democracy from "anti-state forces" and "threats posed by North Korea" — but gave little detail or evidence.
Mr Yoon has long maintained that a hard line against the North is the only way to stop Pyongyang from following through on its nuclear threats against Seoul.
The Associated Press noted that the vague statement was reminiscent of the heavy-handed tactics of previous South Korean dictatorships, when a series of strongmen repeatedly invoked North Korea when struggling to control domestic dissidents and political opponents.
There were quick claims that the emergency declaration was linked to Mr Yoon's political struggles.
The president complained of 22 impeachment motions filed against administration officials since he took office in May 2022.
In recent months, Mr Yoon denied wrongdoing in an influence-peddling scandal involving him and his wife.
The claims have battered his approval ratings and fuelled attacks by his rivals.
The martial law announcement also came in the context of a festering budget row between Mr Yoon and the opposition Democratic Party.
The opposition has slashed around 4.1 trillion won ($4.5 billion) from Mr Yoon's proposed 677 trillion won ($736 billion) budget for next year, prompting the president to complain that "all key budgets essential to the nation's core functions" were being cut.
"What is clear is that Yoon has been a deeply unpopular, ineffectual leader and he is having a hard time getting any kind of public support for anything he's trying to do," said Alan Yu, a former US diplomat in Asia now at the Center for American Progress.
"The use of martial law feels almost like a desperation move to try to break out, both in a political and policy sense, but it is really poorly played on both fronts."
What's been the domestic reaction?
The opposition quickly lambasted Mr Yoon's move as undemocratic, with Democratic Party leader Lee Jae-myung calling the announcement "illegal and unconstitutional".
But the sudden declaration was also opposed by the leader of Mr Yoon's conservative party, Han Dong-hoon, who called the decision "wrong" and vowed to "stop it with the people".
Average South Koreans were mostly in shock. Social media was flooded with messages expressing surprise and worry over Mr Yoon's announcement.
"Martial law? I thought it was deepfake content, but is it really a martial law decree?" one X user wrote.
"I first thought about a war with North Korea when he said he would impose a martial law," posted another.
After martial law was rescinded, protesters outside parliament celebrated with chants of: "We won!"
Cho Kuk, the head of a minor opposition party, has now vowed to impeach Mr Yoon by gathering votes from multiple parties.
Sojin Lim from the University of Central Lancashire told ABC Radio National Breakfast that the president's "radical decision" was a real miscalculation and his impeachment looks "inevitable".
"Already union members have announced that they're going to have a restless strike until the president resigns," she said.
"More and more people are gathering in Seoul, early in the morning and overnight, and people who did not take part in the protest before [are beginning] to join the protest."
What has the response been overseas?
South Korea is a key Western ally in Asia, seen as an important democratic bulwark in a region dominated by authoritarian regimes, and the drama is being watched closely.
Washington voiced "grave concern" about the situation, later expressing relief the president had reversed course.
China, a key ally of nuclear-armed North Korea, urged its citizens to exercise caution, while Russia — itself increasingly close to Pyongyang — called the situation "alarming".
One Western diplomat, speaking to Reuters on condition of anonymity to discuss sensitive politics, said the martial law declaration would complicate conversations about South Korea joining more multinational diplomatic efforts.
"For a president who has focused so much on South Korea's international reputation, this makes South Korea look very unstable," said Mason Richey, a professor at Hankuk University of Foreign Studies.
"This will have a negative effect on financial and currency markets and South Korea's diplomatic place in the world."
The Smartraveller service, run by Australia's Department of Foreign Affairs and Trade (DFAT), also issued new advice for Australians currently in South Korea, telling them to avoid protests and demonstrations.
When did South Korea stop being a dictatorship?
South Korea became a democracy only in the late 1980s, and military intervention in civilian affairs is still a very sensitive subject.
During the dictatorships that emerged as the country rebuilt from the destruction of the Korean War, leaders occasionally proclaimed martial law that allowed them to station combat soldiers, tanks and armoured vehicles on streets or in public places to prevent anti-government demonstrations.
Such scenes are unimaginable for many today.
The dictator Park Chung-hee, who ruled South Korea for nearly 20 years before he was assassinated by his spy chief in 1979, led several thousand troops into Seoul in the early hours of May 16, 1961, in the country's first successful coup.
During his rule, he occasionally proclaimed martial law to crack down on protests and jail critics.
Less than two months after his death, Major General Chun Doo-hwan led tanks and troops into Seoul in December 1979 in the country's second successful coup.
The next year, he orchestrated a brutal military crackdown on a pro-democracy uprising in the southern city of Gwangju, killing at least 200 people.
In the summer of 1987, massive street protests forced his government to accept direct presidential elections.
His former army colleague Roh Tae-woo, who had joined the 1979 coup, won the election held later in 1987 thanks largely to divided votes among liberal opposition candidates.
ABC/wires
