Dubai, United Arab Emirates — Saudi ArabiaThe crown prince said Thursday the kingdom wants to invest $600 billion in the United States over the next four years, comments that came after President Trump priced a return to the kingdom as his first foreign trip.

Mr. Trump’s trip to Saudi Arabia in 2017 he upended the tradition of American presidents first going to the United Kingdom as their first trip abroad. He also highlighted his administration’s close ties to the rulers of the oil-rich Gulf states as his eponymous real estate company also made deals across the region.

Crown Prince Mohammed bin Salman’s comments, reported early Thursday by the state-run Saudi Press Agency, came in a telephone conversation with Mr. Trump.

“The crown prince confirmed the kingdom’s intention to expand its investment and trade with the United States over the next four years, to the tune of $600 billion, and potentially more,” the report said.

The reading did not elaborate on where these investments and trade could be placed. In recent years, the US has increasingly moved away from reliance on Saudi oil exports, which have been the foundation of their relationship for decades. Saudi sovereign wealth funds have taken large stakes in American companies while also eyeing sports.

Saudi Arabia, however, relies heavily on US-made weapons and defense systems, which could be part of the investment.

There were no immediate readings from the White House on call. It was also not immediately clear whether Mr Trump’s conversation with the crown prince was his first with a foreign leader since re-entering the White House. However, it was the first such call to be reported.

The crown prince, de facto ruler of the oil-rich kingdom, also spoke with US Secretary of State Marco Rubio early Thursday.

On the Monday after his inauguration, Mr. Trump talked about possibly returning to the kingdom as his first foreign trip, as he did in 2017.

“The first trip abroad is usually to the United Kingdom, but … the last time I did it was to Saudi Arabia because they agreed to buy $450 billion worth of our products,” Mr. Trump told reporters in the Oval Office. “If Saudi Arabia wanted to buy another $450 billion or $500 — we’ll increase that for all the inflation — I think I’d probably go.”

The kingdom’s 2017 visit triggered a multi-year boycott of Qatar by four Arab nations, including the kingdom.

Mr. Trump maintained a close relationship with Saudi Arabia, even after Prince Mohammed was involved in murder and dismemberment in 2018 Washington Post columnist Jamal Khashoggi in Istanbul. The kingdom has also been in talks with the Biden administration for years about a broader deal recognize Israel in exchange for US defense protection and other support.

The $600 billion pledge, which dwarfs the gross domestic product of many nations, also comes as the kingdom faces its own budget pressures. Global oil prices remain low for years after the peak of the coronavirus pandemic, affecting the kingdom’s revenues.

Meanwhile, Prince Mohammed also wants to continue his $500 billion project in NEOM, a new city in Saudi Arabia’s western desert on the Red Sea. Tens of billions of dollars worth of new stadiums and infrastructure will also need to be built before hosting the 2034 FIFA World Cup.