In Washington, there is not much mystery about Saudi Crown Prince Mohammed bin Salman's (MBS) behavior. He is an ego-maniac, somewhat unhinged. He is drunk with power and accustomed to torture and kill at whim.
His campaign of annihilation against the Houthis of Yemen indicates the depths of his depravity and the scope of his ambition. So, too, did his imprisoning of 400 wealthy Saudis in the Riyadh Ritz Carlton where they were physically abused until they coughed up their riches for his personal use (e.g., spending $500 million for a mislabeled "Leonardo" painting). MBS thus presents a good imitation of Caligula and Nero. So, too, did his kidnapping and physical abuse of the prime minister of Lebanon (Saad Hariri) — who owed MBS money and, therefore, political fealty.
In these ruthless ventures, he has been encouraged by the American government. The Saudi bombing of Yemen to smithereens, literally, could not happen physically without the active participation of the Pentagon.