Yoon supporters gathered in the pre-dawn hours near the presidential residence on Friday, with the numbers swelling into the hundreds as they vowed to block any attempt to arrest Yoon.
Officials from the Corruption Investigation Office for High-ranking Officials (CIO), which is leading a joint team of investigators into Yoon's brief declaration of martial law on December 3, arrived at the gates of the presidential compound shortly after 7am (local time) and entered on foot.
Once inside the compound, the CIO and accompanying police faced cordons of Presidential Security Service (PSS) personnel, as well as military troops seconded to presidential security, media reported. South Korea's Ministry of National Defense said the troops were under the control of the PSS.
The CIO called off the effort to arrest Yoon around 1.30 pm due to concerns over the safety of its personnel due to obstruction, and said it "deeply regretted" Yoon's attitude of non-compliance.
"It was judged that it was virtually impossible to execute the arrest warrant due to the ongoing standoff," the CIO said in a statement.
Yoon's lawyer said in an earlier statement on Friday that execution of an invalid arrest warrant against Yoon, 64, is unlawful, and that they would take legal action, without elaborating.
The arrest warrant, approved by a court on Tuesday after Yoon ignored multiple summons to appear for questioning, is viable until January 6, and gives investigators only 48 hours to hold Yoon after he is arrested. Investigators must then decide whether to request a detention warrant or release him.
The CIO said on Friday it would review the situation and decide on possible next steps.
Yoon is under criminal investigation for insurrection over his martial law attempt that stunned South Korea, Asia's fourth-largest economy and one of the region's most vibrant democracies.
An arrest on Friday would have been the first for an incumbent South Korean president.
"We have to block them with our lives," one was heard saying to others.
Some chanted "President Yoon Suk Yeol will be protected by the people," and called for the head of the CIO to be arrested.
Pyeong In-su, 74, said that the police had to be stopped by "patriotic citizens"- a term Yoon used to describe those standing guard near his residence.
Holding a flag of the United States and South Korea with the words "Let’s go together" in English and Korean, Pyeong said he hoped incoming US President Donald Trump would come to Yoon's aid.
"I hope after Trump's inauguration he can use his influence to help our country get back on the right track."
SURPRISE MARTIAL LAW
Yoon sent shockwaves through the country with a late-night announcement last month that he was imposing martial law to overcome political deadlock and root out "anti-state forces".
Within hours, however, 190 lawmakers had defied the cordons of troops and police to vote against Yoon's order. About six hours after his initial decree, Yoon rescinded it.
He later issued a defiant defence of his decision, saying domestic political opponents are sympathetic to North Korea and citing uncorroborated claims of election tampering.
Kim Yong-hyun, who resigned as Yoon's defence minister after playing a major role in the martial law decree, has been detained and was indicted last week on charges of insurrection and abuse of power.
Insurrection is one of the few criminal charges from which a South Korean president does not have immunity.
Yoon's lawyers have said the arrest warrant was illegal and invalid because the CIO did not have the authority under South Korean law to request a warrant.
Yoon has been isolated since he was impeached and suspended from power on December 14.
Separate from the criminal investigation, his impeachment case is currently before the Constitutional Court to decide whether to reinstate or permanently remove him. A second hearing in that case is scheduled for later on Friday.
