President Yoon Suk-yue of South Korea's attempt to implement martial law lasted only six hours before failing. Observers said that Yoon Suk-yue's short-lived martial law threatens the foundation of the country's democratic system. Several former South Korean presidents have been convicted or impeached for seemingly lighter reasons. Observers also mentioned that Yoon Suk-yue's sudden decision on Tuesday night still poses several legal and procedural issues. Lee Seong-hyon, a researcher at Harvard University's Asia Center, said that compared to his predecessors, Yoon Suk-yue's actions appear "extremely serious, threatening the fundamental of South Korea's democratic system."