TL;DR
Yoon Suk Yeol strongly opposed Lee Jae Myung, viewing him as a threat to the constitutional order following his election.
Key Points
During a debate, Yoon concentrated most of his time questioning Lee on allegations of corruption involving real estate contracts in Seongnam.
Lee Jae Myung, the opposition leader, vowed to make all-out efforts to impeach Yoon following the controversial martial law imposition in December 2024.
After the Constitutional Court upheld Yoon's impeachment, Lee Jae Myung praised the people for "protecting our democratic republic".
Summary
Yoon Suk Yeol, as president, maintained a distinctly adversarial position toward Lee Jae Myung, the leader of the liberal opposition Democratic Party. This was most evident following Yoon's controversial declaration of martial law in December 2024, which Lee and his party immediately sought to overturn and subsequently used as grounds to move for Yoon's impeachment. The opposition leader, Lee, questioned the sitting president's state of mind after the martial law incident and vowed to use all available means to suspend Yoon's power, effectively framing the former president as dangerously erratic.
Prior to the political crisis leading to the snap election, Yoon had already concentrated his political fire on Lee Jae Myung during a 2022 debate, focusing heavily on questioning allegations of corruption against his rival regarding real estate contracts and favors for entities like Doosan Engineering & Construction. Lee's subsequent victory in the June 2025 snap presidential election, which followed Yoon's successful impeachment, cemented their dynamic as one of fundamental political opposition between the former conservative executive and the new liberal leader.
Frequently Asked Questions
Yoon Suk Yeol's position regarding Lee Jae Myung was that of a strong political adversary, particularly during and after the 2024 martial law crisis. The former president viewed Lee, as the leader of the opposition, as a significant challenge to his administration and the political status quo.
Yes, Yoon Suk Yeol criticized Lee Jae Myung even before the impeachment proceedings, heavily focusing on allegations of corruption against his rival during a 2022 presidential debate. He used that platform to question Lee's past conduct related to property dealings while mayor.
Lee Jae Myung aggressively challenged Yoon Suk Yeol, especially after the declaration of martial law, which Lee called an “unconstitutional, illegal rebellion or coup”. Following Yoon's removal, the opposition leader praised the people for defending democracy against the former president's actions.
Sources5
Yoon Suk-yeol concentrates fire on allegations against Lee Jae-myung during debate
South Korea's opposition leader questions President Yoon's state of mind after martial law chaos
Is South Korea's New President Good for Democracy?
Impeachment of Yoon Suk Yeol - Wikipedia
South Korea's new president Lee Jae-myung brings uncertainty to Seoul's foreign policy
* This is not an exhaustive list of sources.