Donald Trump has touched down in Saudi Arabia for his first foreign trip as president.

Arriving in the capital Riyadh, President Trump travelled with the aim of building stronger US-Saudi ties to combat terrorism in the region.

Travelling with wife Melania aboard Air Force One, the US leader was greeted by Saudi King Salman on Saturday.

The president plans to spend two days in Riyadh and becomes the only US leader to make Saudi Arabia, or any majority Muslim country, his first overseas stop.

His decision comes in part to show respect to the region after months of harsh anti-Muslim campaign rhetoric.

As he arrived, President Trump exchanged pleasantries with King Salman, 81, saying it was a "great honour" to be there.

Part of a wider foreign excursion, he will head to Israel after finishing business in Riyadh, before having an audience with Pope Francis at the Vatican.

Finally, he will meet with NATO allies at a summit in Brussels and the Group of 7 wealthy nations in Sicily.