SEOUL, South Korea (AP) — Hours after South Korea's impeached President Yoon Suk Yeol was formally arrested, triggering rioting by his supporters, his lawyers said Sunday that he remains defiant in his refusal to answer questions over the probe into his declaration of martial law last month.

Yoon was formally arrested early on Sunday, days after being apprehended at his presidential compound in Seoul. He faces possible imprisonment over his short-lived imposition of martial law, which set off the country's most serious political crisis since its democratization in the late 1980s.

Yoon’s arrest could mark the beginning of an extended period in custody, lasting months or more.

The decision to arrest Yoon ignited unrest at the Seoul Western District Court, where dozens of his supporters broke in and rioted, destroying the main door and windows. They used plastic chairs, metal beams and police shields that they managed to wrestle away from officers. Some were seen throwing objects and using fire extinguishers, destroying furniture and office machines, smashing glass doors and spraying water on computer servers. They shouted demands to see the judge who had issued the warrant, but she had already left.

Hundreds of police officers were deployed and nearly 90 protesters were arrested. Some injured police officers were seen being treated at ambulance vans. The court said it was trying to confirm whether any staff members were injured and assess the damage to its facilities.

In a statement issued through lawyers, Yoon lamented that the court did not recognize the “just purpose” of his martial law decree but also urged his supporters to express their frustrations peacefully. He called on the police to adopt a lenient stance toward the protesters.

But hundreds of Yoon’s supporters continued to clash with police as they extended their rallies into the evening in front of Seoul’s Constitutional Court, which is holding separate deliberations on whether to formally remove the impeached president from office or reinstate him. At least three protesters were detained at the scene. There were no immediate reports of damage to the court, which was barricaded by police.

Court describes Yoon as threat to destroy evidence

In granting law enforcement’s request for an arrest warrant for Yoon, the Seoul Western District Court said there was a threat he could destroy evidence. Yoon and his lawyers on Saturday had appeared before the court and argued for his release.

The Corruption Investigation Office for High-Ranking Officials, which is leading a joint investigation with police and the military, can now extend Yoon’s detention to 20 days, during which they will transfer the case to public prosecutors for indictment.

Investigators are examining whether Yoon’s Dec. 3 martial law decree amounted to an attempted rebellion. While South Korean presidents have wide-ranging immunity from prosecution while in office, the protection does not extend to allegations of rebellion or treason.

Yoon’s lawyers could also file a petition to challenge the court’s arrest warrant. Yoon rejected a questioning scheduled by investigators and remained at a detention center.

Yoon’s defense minister, police chief and several top military commanders have already been arrested and indicted for their roles in the enforcement of martial law.

Yoon’s lawyer decries his arrest

The crisis began when Yoon, in an attempt to break through legislative gridlock, imposed military rule and sent troops to the National Assembly and election offices. The standoff lasted only hours after lawmakers who managed to get through a blockade voted to lift the measure. The opposition-dominated assembly voted to impeach him on Dec. 14, which left his political fate with the Constitutional Court.

Seok Dong-hyeon, one of Yoon’s lawyers, called the court order for his arrest “the epitome of anti-constitutionalism and anti-rule of law.” He pointed to the riot and said Yoon’s arrest would inspire more anger from his supporters.

Yoon’s People Power Party regretted his arrest but also pleaded for his supporters to refrain from further violence.

The liberal opposition Democratic Party, which drove the legislative effort to impeach Yoon, said his arrest would be a “cornerstone for restoring the collapsed constitutional order.” It also called for stern punishment of the rioters.

The country’s acting leader, Deputy Prime Minister Choi Sang-mok, expressed “strong regret” about the riot, saying it “directly undermines democracy and the rule of law.” He asked for heightened security at the sites related to Yoon’s case, also including the Constitutional Court, and measures to ensure order during protests.

Yoon insists his martial law decree was legitimate

Yoon and his lawyers have claimed that the martial law declaration was intended as a temporary and "peaceful" warning to the liberal opposition, which he accuses of obstructing his agenda with its legislative majority. Yoon says the troops sent to the National Election Commission offices were to investigate election fraud allegations, which remain unsubstantiated in South Korea.

Yoon has stressed he had no intention of stopping the functioning of the legislature. He stated that the troops were sent there to maintain order, not prevent lawmakers from entering and voting to lift martial law. He denied allegations that he ordered the arrests of key politicians and election officials.

Military commanders, however, have described a deliberate attempt to seize the legislature that was thwarted by hundreds of civilians and legislative staff who helped lawmakers enter the assembly, and by the troops' reluctance or refusal to follow Yoon's orders.

If prosecutors indict Yoon on rebellion and abuse of power charges, which are the allegations now being examined by investigators, they could keep him in custody for up to six months before trial.

If the first court convicts him and issues a prison term, Yoon would serve that sentence as the case possibly moves up to the Seoul High Court and Supreme Court. Under South Korean law, orchestrating a rebellion is punishable by life imprisonment or the death penalty.

Police officers stand outside of the Seoul Western District Court after supporters of impeached South Korean President Yoon Suk Yeol broke into the court in Seoul, South Korea, Sunday, Jan. 19, 2025. The letters read "The Seoul Western District Court." (AP Photo/Ahn Young-joon)

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Police officers stand guard as supporters of impeached South Korean President Yoon Suk Yeol try to enter the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (AP Photo/Ahn Young-joon)

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Police officers patrol inside Seoul Western District Court after supporters of impeached South Korean President Yoon Suk Yeol broke into the court in Seoul, South Korea, Sunday, Jan. 19, 2025. (AP Photo/Ahn Young-joon)

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Police officers stand at the Seoul Western District Court after supporters of impeached South Korean President Yoon Suk Yeol broke into the court in Seoul, South Korea, Sunday, Jan. 19, 2025. (AP Photo/Ahn Young-joon)

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Supporters of impeached South Korean President Yoon Suk Yeol gather outside the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (Seo Dae-yeon/Yonhap via AP)

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A vehicle carrying impeached South Korean President Yoon Suk Yeol leaves the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (AP Photo/Ahn Young-joon)

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Police officers stand outside of the Seoul Western District Court after supporters of impeached South Korean President Yoon Suk Yeol broke into the court in Seoul, South Korea, Sunday, Jan. 19, 2025. (AP Photo/Ahn Young-joon)

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Seok Dong-hyeon, one of the lawyers for South Korea's impeached President Yoon Suk Yeol, speaks to the media upon his arrival at the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (AP Photo/Ahn Young-joon)

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Supporters of impeached South Korean President Yoon Suk Yeol, hold signs with a message that translates to; "Release the president", alongside police officers, outside the Western District Court in Seoul, South Korea, Sunday, Jan. 19, 2025. (AP Photo/Ahn Young-joon)

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A vehicle carrying impeached South Korean President Yoon Suk Yeol arrives at the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (Kim Min-Hee/Pool Photo via AP)

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Police officers stand guard at the front gate of the Seoul Western District Court in Seoul, South Korea, Sunday, Jan. 19, 2025. (AP Photo/Ahn Young-joon)

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Police officers stand in front of supporters of impeached South Korean President Yoon Suk Yeol after they illegally climbed over a fence inside the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (AP Photo/Ahn Young-joon)

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Supporters of impeached South Korean President Yoon Suk Yeol stage a rally to oppose his impeachment in Seoul, South Korea, Saturday, Jan. 18, 2025. (AP Photo/Lee Jin-man)

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A supporter of impeached South Korean President Yoon Suk Yeol attends a rally to oppose his impeachment outside the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (AP Photo/Ahn Young-joon)

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Supporters of impeached South Korean President Yoon Suk Yeol stage a rally to oppose his impeachment outside the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (AP Photo/Ahn Young-joon)

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A supporter of impeached South Korean President Yoon Suk Yeol lies down on the ground during a rally to oppose his impeachment outside the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (AP Photo/Ahn Young-joon)

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Police officers detain supporters of impeached South Korean President Yoon Suk Yeol after they illegally climbed over a fence inside the Seoul Western District Court in Seoul, South Korea, Saturday, Jan. 18, 2025. (AP Photo/Ahn Young-joon)

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Protesters against impeached South Korean President Yoon Suk Yeol cheer after a court issued a warrant to formally arrest Yoon over his failed martial law bid, in front of a detention center in Uiwang, South Korea, Sunday, Jan. 19, 2025. (AP Photo/Ahn Young-joon)

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Gaon Choi of South Korea in action during a snowboard halfpipe competition at Laax Open, Saturday, Jan. 18, 2025, in Laax, Switzerland. (Gian Ehrenzeller/Keystone via AP)

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