Thousands of South Koreans gathered in the capital on Saturday for opposing demonstrations as authorities prepared another attempt to arrest suspended President Yoon Suk Yeol over his short-lived martial law decree.

Yoon had resisted arrest last week in a dramatic standoff between his security guards and investigators, following his failed December 3 power grab that triggered South Korea's most severe political crisis in decades.

Protesters, divided into pro- and anti-Yoon factions, converged on central Seoul amid sub-zero temperatures, with one group demanding his arrest and another calling for his impeachment to be invalidated.

The nation has remained tense since Yoon ordered soldiers to storm parliament in an unsuccessful attempt to prevent lawmakers from overturning martial law. Since his impeachment, Yoon has retreated into a fortified stance.

Supporters of Yoon began rallying outside his residence early Saturday morning, ahead of a major demonstration scheduled for 1 pm (0400 GMT) in central Seoul. Separate anti-Yoon protests were planned for 2:30 pm and 4 pm.

Yoon faces criminal charges of insurrection, one of the few crimes exempt from presidential immunity, which could lead to a prison sentence or even the death penalty. If the arrest warrant is executed, he would become the first sitting South Korean president to be taken into custody.

On Friday, Yoon's presidential security chief resigned amid questioning over the guards’ role in blocking his arrest during last week's six-hour standoff, which forced investigators to withdraw over safety concerns.

The Presidential Security Service (PSS), including military personnel, has reinforced Yoon's compound in Seoul with barbed wire and bus barricades.

Acting PSS chief Kim Seong-hun has refused to attend a third summons for questioning, potentially exposing himself to arrest. The PSS defended Kim, stating he "cannot leave his post for even a moment regarding presidential security matters."

The Corruption Investigation Office (CIO) vowed to "prepare thoroughly" for a second attempt to arrest Yoon and warned that anyone obstructing the process could face detention.

According to Yonhap, the National Office of Investigation has mobilized 1,000 investigators in preparation for the renewed effort.

Yoon also faces ongoing impeachment proceedings, with the Constitutional Court set to begin his trial on January 14. The trial will proceed even in his absence and will determine whether to uphold his suspension or reinstate him.

Read more: South Korean opposition’s support dips as Yoon defies arrest