The most senior royal detained was Prince Ahmed bin Abdulaziz, the younger brother of King Salman, who for a time had been the great hope of family members and other critics who wished to block Crown Prince Mohammed, 34, from taking the throne.

The former crown prince who was arrested, Mohammed bin Nayef, is also a former interior minister and longtime American favorite. He had developed close ties to American intelligence agencies during years of work together while he was interior minister. He was ousted from both of those roles by the current crown prince in 2017 and he has effectively been under house arrest since then.

His younger brother, Prince Nawaf bin Nayef, was also detained…

One possible motive for the detentions may have to do with the aging of Prince Mohammed’s father, King Salman, 84. The crown prince could be seeking to lock down potential challengers to his own succession before his father dies or abdicates the throne.