Leading up to the president's departure, White House aides anxious that he might not be able to handle the busy trip to Saudi Arabia, Israel, the Vatican, Brussels and Sicily, and two officials reportedly expressed concerns that Trump would leave subsequent foreign travel to Vice President Mike Pence after the nine-day visit through different time zones and foreign hotels. As a reminder, Saudi Prince Turki al-Faisal, in a May 2016 speech at the Washington Institute for Near East Policy, told Americans not to elect Trump as president because of his position on Muslims; that same prince will be among those who will welcome the president to Saudi Arabia.
The president, who is the first since former President Jimmy Carter to not leave the country during his first 100 days in office, has only visited wife Melania's home country of Slovenia on one occasion, when he met her parents during a day trip before they got married. Bush placed the first copy of the Holy Koran in the White House library, and encouraged Americans to travel to the Muslim world, welcome Muslim students into their homes for cultural exchange and study Arabic.
Trump flew to Riyadh overnight on Air Force One and was greeted by an elaborate welcoming ceremony at Riyadh's airport, punctuated by a military flyover and a handshake from Saudi King Salman.
'Getting ready for my big foreign trip.
President Trump, whose dark, guttural demonization of Muslims was a trademark of his nationalist campaign, arrives here Saturday hoping the Arab world will listen to a new message. However, one aim of Trump's visit is to complete an arms-sales agreement that could be worth $300 billion over 10 years.
"Truth is, nobody knows how Donald Trump is going to act or what he's going to say in meetings of this kind because he's never done it before", summed up Stephen Sestanovich of the Council on Foreign Relations.
Every president going back to Ronald Reagan has started smaller, with their first worldwide journeys taking them to America's neighbors, either Canada or Mexico.
Sunday's speech to dozens of Muslim leaders has been touted as a major event - along the lines of a landmark address to the Islamic world given by Obama in Cairo in 2009.
Muslim leaders may also be looking for Trump to build bridges after allegations of Islamophobia against his administration and its effort to bar travellers from six Muslim-majority countries. "They have to help and I'm sure they will".
"We are not here to lecture - to tell other peoples how to live, what to do or who to be. Will be strongly protecting American interests - that's what I like to do!" he said on Twitter before his departure. He also plans to travel to Israel, the Vatican, Brussels and Sicily.
It is a trip fraught with peril for the real estate magnate, who is known to dislike lengthy travel.
This would cement the theory that the collusion between Trump and Russian Federation leading up the Presidential election did in fact reach the highest levels of government in America. During the campaign, he returned to Trump Tower in NY most nights, even if he had been campaigning on the other end of the country.
Allouch says she hopes that Trump will "clarify his thought on Islam as one of the world's great religions".
His visit to the Gulf is expected to bring lucrative arms contracts for USA firms.
After two days of meetings in Riyadh, Trump will travel to Israel, have an audience with Pope Francis at the Vatican, and meet with allies at a North Atlantic Treaty Organisation summit in Brussels and the Group of 7 wealthy nations in Sicily.
But the Israeli leg of his trip is already awash in controversy - from a row over his visit to Jerusalem's Western Wall, the holiest prayer site for Jews, to Trump's alleged disclosure of Israeli intelligence to Russian officials.
"At these summit meetings you might have 28 heads of state and government and they all want to say something, and the president has to sit and listen to all of them".
The "Arab Nato" summit - being held to develop a security partnership against a growing threat of violent extremism - will also be attended by US President Donald Trump.