South Korea's parliament introduced a motion on Thursday to impeach President Yoon Suk Yeol over a botched attempt to impose martial law, but his party vowed to oppose the move, throwing the process into doubt.

President Yoon Suk Yeol of South Korea is facing proceedings that could remove him from office after his imposition of martial law plunged the country into a political crisis. Members of South Korea’s opposition submitted a motion on Wednesday to impeach Mr. Yoon. Here’s how the process could unfold.