Saudi Arabia first stop on Trump's landmark overseas tour

Donald Trump will put spiritualism at the heart of his first overseas tour as US president with Saudi Arabia, Israel and the Vatican all on his travel itinerary later this month.

With it, Trump will reach out to three of the world's major religious communities with the destinations representing the spiritual centres of Islam, Judaism and Catholicism.

But many have been surprised by the president's choice for his first destination - Saudi Arabia, a once strong ally which has taken a more aggressive and independent line towards regional issues in recent years.

"My first foreign trip as president of the United States will be to Saudi Arabia, then Israel, and then to a place that my cardinals love very much, Rome," Trump announced on Thursday.

Saudi Arabia, the home to Islam's two holiest sites, will be the first stop on the tour. 

Trump's aides told AFP this is an attempt to reach out to the Muslim world after the president's controversial comments about the religion and its followers during his election campaign.

Despite this and a so-called "Muslim ban" being put in place by Trump, Gulf states appear to have warmed to the new president.

In Riyadh Trump will meet Gulf and Middle East leaders where the issue of Iran, militancy and other issues will feature on the agenda.

"Saudi Arabia is the custodian of the two holiest sites in Islam," said Trump, who has frequently been accused of fuelling Islamophobia.

"[I will] begin to construct a new foundation of cooperation and support with our Muslim allies to combat extremism, terrorism and violence and to embrace a more just and hopeful future for young Muslims in their countries."

It will also make a reversal of the US' disengagement from the Middle East, which led to strained relations between Riyadh and Washington under Barack Obama's presidency.

It will also likely send out a message to the Gulf power Iran that it will take Saudi Arabia and the UAE's side in any further tensions between the two blocs.

Saudi Arabia has been a key and long-term ally of the US but the decision to make Riyadh Trump's first destination as president has been described as "unorthodox".

Every US presidents since Jimmy Carter has been to either Mexico or Canada, but both of these neighbours have a troubled relationship with Trump.

"It seems to me part of a conscious effort to draw a distinction between the Trump administration and its predecessor," said Eric Pelofsky, a visiting fellow at the Washington Institute for Near East Policy and Obama's National Security Council senior director for North Africa and Yemen told AFP.

"Going there first, rather than Israel or one of our neighbors - Canada or Mexico - is clearly purposeful, potentially building a foundation for other moves like in the Middle East peace process, Iran, and perhaps elsewhere."  

It also sends out the message to Saudi Arabia that the US wants to keep Riyadh as a major regional ally and will work with it on key issues such as curbing Iranian expansionism and the Israel-Palestine peace process.

In March, Saudi Arabia's Deputy Crown Prince Mohammed bin Salman al-Saud visited Trump at the White House, while senior Trump officials have also made the trip to Riyadh.

The US is said to be providing some support to Saudi Arabia in its fight against Houthi rebels in Yemen.

Saudi Arabia also strongly backed a US missile strike on a Syrian regime airbase earlier this year, while Riyadh has warmed to Washington's most combative rhetoric against Iran.

Agencies contributed to this story.