US president Donald Trump has recently been in Saudi Arabia and Israel, but left the Middle East on Tuesday to make his first official visit to the Vatican.

Trump will meet Pope Francis in Rome today on the third leg of his first international trip since taking office.

The pair are expected to clash on a number of key issues from global warming to migration.

In February 2016, the pontiff publicly criticised the then presidential candidate’s key proposal to build a wall along the US-Mexico border.

“A person who thinks only about building walls, wherever they may be, and not building bridges is not Christian,” Francis said at the time.

Trump responded to the Pope’s attack.

No leader, especially a religious leader, should have the right to question another man’s religion or faith,” he said. “They’re using the pope as a pawn, and they should be ashamed of themselves — that’s the Mexican government — they should be ashamed of themselves for doing so, especially when so many lives are involved and when illegal immigration is so rampant and so dangerous and so bad for the United States.

However, more recently, the Pope has adopted a milder approach to Trump.

“I will tell him what I think. He will tell me what he thinks. But I never wanted to judge someone before I listen to the person first,” he said in relation to his upcoming meeting with the US president.

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The papal biographer Austen Ivereigh said the focus of the meeting in Rome would be about building a relationship of mutual support.

He [ the Pope] will be looking to develop a relationship of trust which can later be used by both or either of them to help people or help the church. It is not about sitting down and talking about immigration or Islamic terrorism.

Former US president Barack Obama spent almost an hour with the Pope at their first meeting in 2014, while Canada’s former prime minister Stephen Harper got only about 10 minutes with the religious leader.

While Trump is taking care of his presidential affairs; meeting with Italian prime minister Paolo Gentiloni and other government officials, his wife Melania will visit a Vatican-owned children’s hospital.

Trump will spend less than 24 hours in Italy before flying to Brussels for talks with EU and NATO chiefs.

He will return to Italy on Thursday for a G7 summit in Sicily.