Former South Korean President Yoon Suk Yeol was found guilty of leading an insurrection on Thursday and sentenced to life in prison for his brief imposition of martial law in 2024, a ruling that marks a dramatic culmination of the country's biggest political crisis in decades.

The conservative leader was ousted from office after he declared martial law and sent troops to surround the National Assembly on Dec. 3, 2024, in a baffling attempt to overcome a legislature controlled by his liberal opponents.

Judge Jee Kui-youn of the Seoul Central District Court said he found Yoon, 65, guilty of rebellion for mobilizing military and police forces in an illegal attempt to seize the Assembly, arrest political opponents and establish unchecked power for an indefinite period.

Yoon's martial law imposition, the first of its kind in more than four decades, recalled South Korea's past military-backed governments when authorities occasionally proclaimed emergency decrees that allowed them to station soldiers, tanks and armored vehicles on streets or in public places such as schools to prevent anti-government demonstrations.

As lawmakers rushed to the National Assembly, Yoon's martial law command issued a proclamation declaring sweeping powers, including suspending political activities, controlling the media and publications, and allowing arrests without warrants.

The decree lasted about six hours before being lifted after a quorum of lawmakers managed to break through a military blockade and unanimously voted to lift the measure.

Yoon was suspended from office on Dec. 14, 2024, after being impeached by lawmakers and was formally removed by the Constitutional Court in April 2025. He has been under arrest since last July while facing multiple criminal trials, with the rebellion charge carrying the most severe punishment.

An expressionless Yoon gazed straight ahead as the judge delivered the sentence in the same courtroom where former military rulers and presidents have been convicted of treason, corruption and other crimes over the decades.

Yoon Kap-keun, one of the former president's lawyers, accused the judge of issuing a predetermined verdict based solely on prosecutors' arguments and said the rule of law had collapsed. He said he would discuss whether to appeal with his client and the rest of the legal team.

Former President Yoon claimed in court that the martial law decree was only meant to raise public awareness of how the liberals were paralyzing state affairs, and that he was prepared to respect lawmakers if they voted against the measure.

Prosecutors said it was clear Yoon was attempting to disable the legislature and prevent lawmakers from lifting the measure through voting, actions that exceeded his constitutional authority even under martial law.

The court also convicted and sentenced five former military and police officials involved in enforcing Yoon's martial law decree. They included ex-Defense Minister Kim Yong Hyun, who received a 30-year jail term for his central role in planning the measure, mobilizing the military and instructing military counterintelligence officials to arrest 14 key politicians, including National Assembly speaker Woo Won-shik and current liberal President Lee Jae Myung.

In announcing Yoon and Kim's verdicts, Jee said the decision to send troops to the National Assembly was key to his determination that the imposition of martial law amounted to rebellion.

As Yoon arrived in court, hundreds of police officers watched closely as Yoon supporters rallied outside a judicial complex, their cries rising as the prison bus transporting him drove past. Yoon's critics gathered nearby, demanding the death penalty.

There were no immediate reports of major clashes following the verdict.

A special prosecutor had demanded the death penalty for Yoon Suk Yeol, saying his actions posed a threat to the country's democracy and deserved the most serious punishment available, but most analysts had expected a life sentence since the poorly-planned power grab did not result in casualties.

South Korea has not executed a death row inmate since 1997, in what is widely seen as a de facto moratorium on capital punishment amid calls for its abolition.

Jung Chung-rae, leader of the liberal Democratic Party, which led the push to impeach and remove Yoon, expressed regret that the court stopped short of the death penalty, saying the ruling reflected a lack of a sense of justice.

Song Eon-seok, floor leader of the conservative People Power Party, to which Yoon once belonged, issued a public apology, saying the party feels a deep sense of responsibility for the disruption to the nation.

The office of current President Lee Jae Myung did not immediately comment on the ruling.

Last month, Yoon was sentenced to five years in prison for resisting arrest, fabricating the martial law proclamation and sidestepping a legally mandated full Cabinet meeting before declaring the measure.

The Seoul Central Court had previously convicted two other members of Yoon's Cabinet in connection with the martial law debacle. That includes Prime Minister Han Duck-soo, who received a 23-year prison sentence for attempting to legitimize the decree by forcing it through a Cabinet Council meeting, falsifying records and lying under oath. Han has appealed the verdict.

Yoon is the first former South Korean president to receive a life sentence since former military dictator Chun Doo-hwan, who was sentenced to death in 1996 for his 1979 coup, a bloody 1980 crackdown on pro-democracy protesters in Gwangju that left more than 200 people dead or missing, and corruption.

The Supreme Court later reduced his sentence to life imprisonment, and he was released in late 1997 under a special presidential pardon. He died in 2021.