After an overnight flight, the president was greeted at the airport by King Salman, which was notable given that the monarch did not show up previous year to welcome President Barack Obama on his final visit to Saudi Arabia.
U.S. President Donald Trump arrived on Saturday in Riyadh as part of a two-day trip to discuss cooperation, especially in counterterrorism, Al Arabila local news reported.
A few hours later, Trump tweeted for the first time on worldwide soil as president, writing "Great to be in Riyadh, Saudi Arabia".
Trump intends to condemn Syria's President Bashar Assad for committing "unspeakable crimes against humanity" and Iran for contributing to spiraling violence in Syria.
As US President Donald Trump starts his first official visit to Saudi Arabia on Saturday, he is being carefully watched in light of comments he has made, both during his election campaign and after gaining the presidency, that have been seen by many as hostile both to Islam and Muslims.
On the drive to the Ritz hotel where Trump is staying, King Salman rode with the president in the heavily armored presidential limousine nicknamed "the Beast". In 2015, her husband had, in a tweet, criticized former first lady Michelle Obama for not wearing a headscarf during a visit to the kingdom.
The White House says the agreements include military sales of about $100 billion, effective immediately, plus another $350 billion over the next 10 years.
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Several jets then flew overhead leaving a red, white and blue trail.
On his Saudi trip, Trump has said he will ask Muslim leaders "to fight hatred and extremism and embrace a peaceful future for their faith". He is also hoping to move past the controversies engulfing his administration.
The second version, which dropped Iraq from the list, is also blocked in court, though Trump has said the measure is needed for the nation's security.
The visit is aimed at building stronger partnerships to combat terrorism in the region.
White House chief of staff Reince Priebus told reporters on the plane that Trump spent the flight meeting with staff, working on his upcoming speech to the Muslim world and catching up on a little sleep. He's the only American president to make Saudi Arabia, or any majority Muslim country, his first stop overseas as president.
Finally, he will meet with North Atlantic Treaty Organisation allies at a summit in Brussels and the Group of 7 wealthy nations in Sicily.
Abandoning some of the harsh anti-Muslim rhetoric of his presidential campaign, the draft of the speech, slated to be delivered in Saudi Arabia on Sunday, envisions new partnerships with America's traditional allies in the Middle East.