South Korea faces a deepening leadership crisis as prosecutors name President Yoon Suk Yeol a subject of a criminal investigation following his attempt to impose martial law last week. Yoon survived an impeachment vote, but his party announced plans for him to relinquish authority before resigning. The fallout from Yoon’s martial law declaration has sparked South Korea's most severe political crisis in decades. Analysts warn the crisis could embolden North Korea amid strained allied defenses.