Prosecutors in South Korea have indicted impeached President Yoon Suk Yeol on charges of leading a rebellion after his brief declaration of martial law last month. 

Yoon went on television in early December and abruptly announced he was outlawing all political activity by South Korea’s opposition party because of a need to protect the country from “North Korean communist forces” and “antistate forces,” and to “rebuild and protect” South Korea from “falling into ruin.” He rescinded his martial law decree after six hours after a majority in the assembly voted to overturn it.

Yoon was impeached by the opposition-led parliament on December 14. He was then arrested on January 15 after a dayslong standoff between his security detail and authorities.

Yoon’s defense team has called on prosecutors to immediately release Yoon and launch an investigation into the Corruption Investigation Office for High-Ranking Officials, which was involved in investigating Yoon’s martial law declaration.

“The prosecution has decided to indict Yoon Suk Yeol, who is facing charges of being a ringleader of insurrection,” Democratic Party spokesman Han Min-soo said, according to Reuters. “The punishment of the ringleader of insurrection now begins finally.”

The conservative leader’s presidential immunity does not extend to allegations of rebellion or treason, which is punishable by life in prison or the death penalty in South Korea.

As for his impeachment, the Constitutional Court is weighing whether to reinstate him or formally end his tenure.