President Trump backed Saudi Arabian leaders Monday, following surprise arrests over the weekend of influential Saudi princes, military officers, businessmen, and governmental ministers overseen by the crown prince of Saudi Arabia, Mohammed bin Salman.

“I have great confidence in King Salman and the Crown Prince of Saudi Arabia, they know exactly what they are doing,” Trump tweeted. “Some of those they are harshly treating have been ‘milking’ their country for years!”

Those arrested on Saturday include billionaire Prince Alwaleed bin Talal and two of the late King Abdullah’s sons, according to the Associated Press. Alwaleed is one of the most affluent men in the world and has massive holdings in Western companies. Some of those arrested are adversaries or critics of the crown prince.

The arrests signal that his father, King Salman, is behind his son’s efforts to initiate anti-corruption reforms to gut senior royals and create greater transparency. Trump’s son-in-law and White House senior adviser Jared Kushner has visited the country three times this year.

Trump is currently headed to South Korea as part of his 13-day trip across Asia, where he will be meeting with South Korean President Moon Jae-in.