Police officers forcibly remove President Yoon Suk Yeol's supporters lying on a road in front of the presidential residence in Seoul during a rally in support of Yoon, Thursday. Yonhap

President Yoon Suk Yeol is urging his supporters to "fight together to protect this country against anti-state forces," sparking protests in response to an ongoing investigation into his botched martial law order and subsequent impeachment proceedings.

He is also raising questions about the legitimacy of a detention warrant issued against him, while law enforcement authorities are moving to execute it — a move believed to be a tactic to delay the investigation.

On Thursday, hundreds of Yoon's supporters staged a rally in front of the presidential residence in central Seoul, in an apparent attempt to physically prevent investigators from the Corruption Investigation Office for High-ranking Officials (CIO) from executing the warrant to detain the president. Later in the day, the police forcibly dispersed dozens of supporters who stepped out onto the road, blocking traffic.

Their protest, which had been taking place for weeks, intensified and swelled in size on Wednesday night after Yoon delivered a rallying message to his supporters.

He thanked the protesters who "are making efforts to protect free democracy and the constitutional order of this country" in the cold weather, in a message that was delivered to the supporters in front of the residence on a sheet of A4 paper and also made public by Yoon's legal adviser, Seok Dong-hyeon.

"Korea is currently in danger due to activities of anti-state forces as well as internal and external forces threatening national sovereignty. I will fight until the end to protect this country," he said in the message.

Yoon declared, "I'm watching you on YouTube livestream," prompting conservative YouTubers among the protesters to increase their broadcasts, amplifying coverage of the event.

Amid the intensifying protest, concerns are growing over the possibility of physical clashes between the protesters and CIO investigators who plan to detain Yoon.

On Tuesday, the Seoul Western District Court issued a warrant to detain Yoon on charges of leading an insurrection and abuse of power regarding his martial law decree on Dec. 3, 2024, which was later lifted by the National Assembly. The warrant is valid until next Monday.

This is the first warrant ever issued to detain a sitting president in the nation's history. With the warrant, investigators can detain Yoon for questioning for up to 48 hours. If they want to arrest him, they have to ask the court to issue a separate arrest warrant.

The CIO requested the warrant because Yoon ignored all three summons to appear for questioning. It is coordinating with the police over the timing and method to execute the warrant. It also requested the Presidential Security Service (PSS) to cooperate, warning that any attempt to block the proceeding to detain Yoon could amount to abuse of power and obstruction of public duty.

The staff from the Presidential Security Service and police officers stand guard in front of the presidential residence in Seoul, Thursday. Newsis

However, Yoon's attorney Yoon Gap-geun said the CIO has no right to mobilize the police to detain the embattled president.

"The attempt by the CIO to detain Yoon and search the presidential residence through the support of police is illegal. Arrest and search warrants must be directly executed by prosecutors and investigators of the CIO," the attorney said.

He even suggested that police officers attempting to execute the warrant on behalf of the CIO could be detained by the PSS or "any citizen" for abuse of power or obstruction of public duty — a statement critics say could incite Yoon's supporters outside the residence to physically block investigators.

In previous search attempts, the PSS blocked investigators from entering Yoon's office and residence, citing national security concerns.

The president's message angered the opposition, who accused him of inciting his supporters to clash with the authorities.

"Instead of reflecting on himself, the president is inciting civil war. The joint investigation team of the CIO, the police and the defense ministry's investigation unit should no longer delay executing the warrant and arrest Yoon, the insurrection ringleader, immediately today," said Rep. Park Chan-dae, floor leader of the main opposition Democratic Party of Korea.

Rep. Lee Jun-seok of the minor conservative Reform Party, who previously led the ruling People Power Party (PPP) as chairman, said it is unbelievable that Yoon continues to view the world from the perspective of far-right YouTube channels.

"The last thing Yoon can do for Korea is to immediately resign. I don't care if I'm not able to run for the next presidential election. I just hope Korea goes back to its normal state as soon as possible," Lee wrote on his Facebook page. Lee will be eligible to run in a presidential election after March 31 when he turns 40.

President Yoon Suk Yeol's supporters lie on the road in front of police officers during a rally at the entrance of the presidential residence in Hannam-dong, Seoul, Thursday, to block the Corruption Investigation Office for High-ranking Officials from executing a warrant to detain Yoon in its investigation into his botched martial law. Later in the day, the police forcibly removed them from the road. Yonhap

Yoon's message also irked several lawmakers from the ruling PPP.

"Yoon needs to stop making nonsensical excuses and playing with words," Rep. Kim Sang-wook said in a radio interview.

In addition to the ongoing criminal investigation, the embattled president is also undergoing an impeachment trial at the Constitutional Court, accused of abuse of power and insurrection.