US President Donald Trump arrived in Saudi Arabia on Tuesday to kick off a four-day swing through the Gulf region, focusing more on economic deals than security crises ranging from war in Gaza to the threat of escalation over Iran's nuclear program.

With a who's who of powerful American business leaders in tow, including Tesla CEO and Trump adviser Elon Musk, he will first visit Riyadh, site of a Saudi-US Investment Forum, heading to Qatar on Wednesday and the United Arab Emirates on Thursday.

"While energy remains a cornerstone of our relationship, the investments and business opportunities in the kingdom have expanded and multiplied many many times over," Saudi Investment Minister Khalid al-Falih said as he opened the forum.

"As a result ... when Saudis and Americans join forces very good things happen, more often than not great things happen when those join ventures happen," he said ahead of Trump's arrival.

The Saudi-US investment forum began with a video showing soaring eagles and falcons that celebrated the long history between the United States and the kingdom.

At the front of a palatial hall sat Larry Fink, the CEO of Blackrock, Stephen A Schwartzman, the CEO of Blackstone, Treasury Secretary Scott Bessent and Saudi Finance Minister Mohammed Al Jadaan and Khalid.

Saudi Arabia and the Unites States have maintained strong ties for decades based on an ironclad arrangement in which the kingdom delivers oil and the superpower provides security.

Trump has also said he may travel on Thursday to Turkey for potential face-to-face talks between Russian President Vladimir Putin and Ukrainian President Volodymyr Zelenskiy.

In addition to pressing for a settlement to the war in Ukraine, his administration is pushing for a new aid mechanism for war-torn Gaza and urging Israeli Prime Minister Benjamin Netanyahu to agree a new ceasefire deal there.

Over the weekend, US and Iranian negotiators met in Oman to discuss a potential deal to curb Tehran's nuclear programme. Trump has threatened military action against Iran if diplomacy fails.

Apart from the possible Turkey side trip, those matters are not the focus of Trump's Middle East swing as now scheduled, however.

The United States, Saudi Arabia, Qatar and the UAE are expected to announce investments that could run into the trillions. Saudi Arabia already committed in January to US$600 billion in investments in the United States over the next four years, but Trump has said he will ask for a full trillion.

In addition to Musk, business leaders including BlackRock CEO Larry Fink and Citigroup CEO Jane Fraser will make the trip.

Secretary of State and National Security Adviser Marco Rubio and Secretary of Defense Pete Hegseth will travel with the president.

During the Riyadh stop, Trump is expected to offer Saudi Arabia an arms package worth well over US$100 billion, sources said, which could include a range of advanced weapons including C-130 transport aircraft.

Trump's second and third stops, in Qatar and the UAE, are similarly expected to focus on economic issues.

Qatar's royal family is expected to gift Trump a luxury Boeing 747-8 plane to be outfitted for use as Air Force One, an arrangement that has drawn scrutiny from ethics experts.

Trump is expected to donate the plane to his presidential library for use after his term ends. (Reuters)