Trump Praises Saudi Rulers After Purge: 'They Know What They Are Doing'

Trump says he has 'great confidence in King Salman and Crown Prince of Saudi Arabia' following mass arrests of princeses and top businessmen

FILE - In this May 21, 2017 file photo, released by the Saudi Press Agency, from left to right, Egyptian President Abdel Fattah al-Sissi, Saudi King Salman, U.S. First Lady Melania Trump and President Donald Trump, visit a new Global Center for Combating Extremist Ideology, in Riyadh, Saudi Arabia. Egyptג€™s Foreign Ministry has cancelled a meeting with senior White House advisor Jared Kushner after the U.S. announced aid cuts and delays to Egypt earlier. Kushner arrived on Wednesday, Aug. 23, 2017 on top of U.S. delegation that includes Jason Greenblatt, envoy for international negotiations, and Dina Powell, deputy national security adviser to discuss the possibility of resuming the Israeli-Palestinian peace process. (Saudi Press Agency via AP, File)
Uncredited/AP

U.S. President Donald Trump on Monday endorsed a move by Saudi Arabia's future king who tightened his grip on power through an anti-corruption purge by arresting royals, ministers and investors. 

Trump, who has cultivated much warmer ties with Riyadh than his predecessor Barack Obama, tweeted on Monday that he has "great confidence in King Salman and the Crown Prince of Saudi Arabia" following the mass arrests, which was the biggest anti-corruption purge of the kingdom's affluent elite in its modern history. 

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Trump also tweeted that "they know exactly what they are doing," adding: "Some of those they are harshly treating have been 'milking' their country for years." 

Among those arrested were billionaire investor Alwaleed bin Talal who is one of the kingdom's most prominent businessmen. 

The purge is the latest in a series of dramatic steps by Crown Prince Mohammed bin Salman to assert Saudi influence internationally and amass more power for himself at home. 

Trump's first trip abroad as president was to Saudi Arabia where King Salman gave him a remarkably warm greeting. U.S.-Saudi ties had been strained under the Obama administration, whom they felt considered Riyadh's alliance with Washington less important than negotiating the Iran nuclear deal.