The Wall Street Journal reports on Mohammed bin Salman’s latest purge:

Saudi Arabian authorities detained two of the kingdom’s most prominent figures for an alleged coup attempt, further consolidating the power of the king’s son, Crown Prince Mohammed bin Salman, and clearing away once-formidable rivals to the throne, according to people familiar with the matter.

The detentions occurred early Friday morning when guards from the royal court wearing masks and dressed in black arrived at the homes of the two men, took them into custody and searched their homes, according to people familiar with the matter.

Prince Ahmed bin Abdulaziz al Saud, a brother of Saudi King Salman, and Prince Mohammed bin Nayef bin Abdulaziz al Saud, the king’s nephew known as MBN, were both accused of treason, the people said. The guards also arrested one of MBN’s brothers.

The Saudi royal court accused the two men of plotting a coup to unseat the king and crown prince, according to people familiar with the situation.

The crown prince has been steadily consolidating power over the last two years, but this is a much more aggressive move against senior members of the royal family than we have seen before. Accusing such prominent royals of treason suggests that the crown prince is very nervous about his grip on power. Ever since Mohammed bin Nayef was pushed aside so that the king’s son could be made crown prince, he has been kept under house arrest, so something must have happened to push Mohammed bin Salman to take such drastic action against his uncle and cousins. There would be no need for him to move to eliminate potential rivals for the succession unless he was afraid that his succession was in doubt. If Mohammed bin Nayef and his father and brother are executed for their alleged treason, that will be the clearest sign yet that the crown prince is completely out of control.

Hauling away senior members of his own family is another example of the crown prince’s increasing repression. Not even some of his closest relatives can escape his brutal crackdowns. Like his earlier purges, this is undoubtedly intended to terrify other dissenters into staying quiet. It is possible that the crown prince has once again miscalculated and overreached. Mohammed bin Salman has already made many enemies with his previous power grabs, and this could end up being one power grab too many. These arrests were supposedly to thwart a coup, but they might very well trigger unrest and opposition to the crown prince. Whether this latest move backfires on him or not, it shows Mohammed bin Salman to be the reckless despot that his critics have claimed him to be. The U.S. should have nothing more to do with him, and the U.S.-Saudi relationship should be downgraded for as long as he remains in power.

It is not the role of the U.S. to decide who becomes the next Saudi king, but our government does decide what our relationship will be with the kingdom. We have known for years that Mohammed bin Salman is an incompetent and dangerous ruler whose worst habits have been encouraged by unceasing U.S. support. One of the top priorities of the next administration ought to be to cut off all support to the Saudi government in recognition that the U.S. doesn’t need the Saudis and shouldn’t want to be implicated in any more of their crimes.