Yoon said he's cooperating to avert "bloodshed" but invoked his right to remain silent and his lawyers are using "every legal tactic" in the book, analysts say, against the insurrection probe into his ill-fated declaration of martial law.

The charges are unprecedented for a South Korean president, and if convicted, Yoon Suk Yeol could face years in prison for his shock martial-law decree, which sought to ban political and parliamentary activity and control the media.

President Yoon Suk Yeol of South Korea has been indicted for leading an insurrection related to his imposition of martial law on Dec. 3. He was impeached by parliament and has been in custody since Jan.