Jordanian officials have detained at least 20 people, including the former crown prince, on suspicion that they were plotting to overthrow King Abdullah II bin Al-Hussein, The Washington Post reports. The arrests reportedly come after palace authorities uncovered an elaborate plot involving security officials, tribal leaders, and members of the royal family—including former Crown Prince Hamzah bin Hussein, the king’s half-brother—to unseat the sitting monarch in a move that could seriously “threaten the country’s stability,” according to a Jordanian palace advisor who spoke to the Post. Others arrested as part of the attempted coup include royal family member Sharif Hasan and former senior official Bassem Awadullah. A Jordanian intelligence official added that additional arrests are likely.