Donald Trump enjoyed a lavish, royal welcome in Saudi Arabia on Tuesday on the first state visit of his second term, with the US president foremost focused on business deals at the start of a Gulf tour.

Saudi Arabia escorted Air Force One with fighter jets before bringing out long-stretching honour guards both at the airport and a palace decked out with imposing chandeliers.

With cameras rolling, a lengthy procession of Saudi royalty and business figures waited their turn to shake hands with Trump and Saudi Arabia's de facto ruler, Crown Prince Mohammed bin Salman, who stood by his side.

Trump brought along top members of his cabinet as well as US business figures including his adviser Elon Musk, the world's richest person, who made a rare appearance in a suit as he chatted to the prince.