Supporters of impeached President Yoon Suk Yeol stage a rally in front of the Seoul Detention Center in Uiwang, Gyeonggi Province where Yoon is detained, Jan. 17. Yonhap

President Yoon Suk Yeol on Friday expressed his gratitude to supporters for their "patriotism" in a letter released after investigators sought an arrest warrant against him.

Yun Gap-geun, Yoon's defense attorney, shared the letter titled "President Yoon's letter to people at the Seoul Detention Center," shortly after the Corruption Investigation Office for High-ranking Officials requested a warrant from the Seoul Western District Court.

"Greetings to the people. I am doing well in the detention center, though it is a bit uncomfortable," Yoon wrote.

He mentioned rereading key speeches from his presidency, including his inauguration address and Liberation Day remarks, as part of his reflection on national politics.

"I have heard that many people are coming out into the cold streets to gather strength for the country," he added. "I am grateful for your passionate patriotism."

Yoon was detained on Wednesday on charges of insurrection and abuse of power related to his botched imposition of martial law on Dec. 3. (Yonhap)