South Korea’s President Yoon Is Indicted

South Korea’s impeached and arrested president, Yoon Suk Yeol, was formally indicted on Sunday on charges of leading an insurrection last month when he briefly imposed martial law, prosecutors said.

Mr. Yoon’s indictment means that his trial is likely to start soon. It follows the indictments of a former defense minister and several military generals and police chiefs, all of whom face criminal charges of helping Mr. Yoon commit the same crime.

He is the first president in South Korean history to face criminal charges while still in office.

His downfall began when he unexpectedly declared martial law on Dec. 3, accusing the opposition-controlled National Assembly of “paralyzing” his government. The Assembly voted the measure down, forcing him to rescind the order after about six hours. But it has set off South Korea’s worst political crisis in decades.

As people called for Mr. Yoon’s ouster, the Assembly impeached him on Dec. 14, suspending him from office. The country’s Constitutional Court is deliberating whether the parliamentary impeachment was legitimate and if he should be formally removed from office. Separately, criminal investigators detained Mr. Yoon on the insurrection charges on Jan. 15.

From his jail cell, Mr. Yoon has vowed to fight to regain office.

A majority of South Koreans approved of his impeachment and consider him guilty of insurrection, according to public opinion polls. But Mr. Yoon’s die-hard supporters have called his impeachment “fraud.” Some of them shocked the country when they vandalized a courthouse in Seoul after one of its judges approved a warrant to arrest him on Jan. 19. Nearly 60 people were arrested in connection with that unrest.

Prosecutors said that Mr. Yoon committed insurrection during the short-lived imposition of martial law when, they said, he banned all political activities and ordered military commanders to break the Assembly’s doors down “with axes” or “by shooting, if necessary” and “drag out” lawmakers. They said Mr. Yoon sent the troops there to seize the Assembly and detain political leaders.

The nation watched the live-streamed scenes of special forces troops armed with assault rifles storming the Assembly as lawmakers were gathering there to vote against martial law. But Mr. Yoon has rejected the charge of insurrection, saying that he never intended to neutralize the Parliament or arrest political leaders. The troops were there to “keep order,” he said.

Mr. Yoon’s indictment, although not a surprise, came sooner than expected.

State prosecutors have been investigating the former defense minister and generals. The country’s Corruption Investigation Office for High-ranking Officials took on the insurrection case against Mr. Yoon, but by law, only prosecutors can indict him.

Mr. Yoon has refused to cooperate with the inquiry; he and his lawyers have insisted that the four-year-old office has no right to investigate him.

On Thursday, the Corruption Investigation Office handed his case over to prosecutors. The two had earlier agreed that prosecutors had until early February to indict Mr. Yoon, and prosecutors had planned to further investigate Mr. Yoon’s actions.

But on Friday, a judge in a Seoul court ruled that Mr. Yoon must be either be indicted sooner or released because the Corruption Investigation Office had already done an investigation.