Police officers and security guards tighten up security of the Seoul Western District Court on January 20, the day after mob violence by President Yoon Suk-yeol’s supporters occurred. Reporter Jeong Ji-yoon

An unprecedented violence by President Yoon Suk-yeol’s supporters at Seoul Western District Court has had wide repercussions. Tensions were high throughout the day as Yoon’s supporters flocked to the Constitutional Court, the National Human Rights Commission, and the Seoul Detention Center on January 20 and a series of “terror warnings” were posted online. Targeted agencies canceled events or increased security, and the police expanded their investigations. There are widespread fears that the unbridled rampage and violence unleashed by the incident where Yoon’s supporters stormed the Seoul Western District Court to protest a judge’s decision to officially issue an arrest warrant for Yoon could recur at key stages of his impeachment trial and criminal trial proceedings.

The area in front of the Constitutional Court in Jongno-gu, Seoul, where Yoon's impeachment trial is underway, was packed with his supporters on the day. In front of the main entrance of the Constitutional Court and across the street from it, more than 100 protesters, including lone protesters carrying the Korean national flag and the American flag, and the National Union of People against Impeachment, gathered in the afternoon. The police deployed 10 riot police buses and drew a cordon around the main entrance of the court. The day before the mob violence at the Seoul Western District Court, hundreds of protesters gathered in front of the Constitutional Court and three protesters were detained by the police for trying to climb over its wall.

The Constitutional Court tightened security around the building. “We have requested the police to strengthen the security of the courtroom and the perimeter,” said Cheon Jae-hyun, a public information officer for the Constitutional Court, at a press briefing. The court has increased the number of security guards and stepped up security checks of people entering the court. It has decided to remain on call after work for the time being.

The sparks also flew in the National Human Rights Commission (NHRC). It canceled a plenary committee meeting. As soon as it became known that the commission was going to hold a plenary committee meeting to discuss whether or not to present the agenda of “guaranteeing President Yoon Suk-yeol's right to defense,” far-right groups were poised to swarm the commission. HoverLab, which operates a YouTube channel, had called for people to gather at the NHRC the day before, saying, “The leftists of the Korean Confederation of Trade Unions are breaking into the NHRC and interfering with legitimate meetings, and the people on the right should also go and fight.” An official of the NHRC said, "As there were posts threatening the HRC in the online community, we decided to postpone the plenary committee meeting out of concern for possible disturbances.”

In fact, far-right YouTubers broadcast throughout the day in front of the NHRC building, while supporters of Yoon rallied to “guarantee human rights for the president.” When news broke that the NHRC had postponed the meeting, they finished the rally and moved to the Constitutional Court.

Rallies in support of Yoon have also been taking place for days in front of the Seoul Detention Center in Uiwang, Gyeonggi Province, where Yoon has been held. Dozens of people, including far-right YouTubers and Yoon's supporters, gathered in front of the detention center, holding the Korean national flags, the American flags, and signs that read, “Support for Yoon Suk-yeol.” “We must take the president out of the detention center even by force,” said Jeon Kwang-hoon, head pastor at Sarang Jeil Church in Seoul, at a rally in front of the Seoul Western District Court on January 18.

On online communities, some said, "I will set fire to the Constitutional Court," "Wouldn't it be better to go to the National Assembly and kill all Democratic Party of Korea lawmakers without fighting with the police?" and "Tomorrow, 10,000 people will gather to storm each targeted places (the Constitutional Court, media companies, and the National Assembly)." The police have launched an investigation into the terrorist threats posted in online communities. The Cyber Investigation Bureau of the Seoul Metropolitan Police Agency and the Cyber Investigation Bureau of the Gyeonggi Southern Police Agency said that they have begun an internal investigation into the writers of online posts warning of terrorist attacks on the Constitutional Court, media companies, and the National Assembly.