Saudi Arabia said it will invest at least $600 billion in the US over the next four years.President Donald Trump has long enjoyed a good relationship with Saudi Arabia's crown prince.Trump has moved quickly since taking office, signing executive orders and announcing investments.Saudi Arabia's Crown Prince Mohammed bin Salman has told newly inaugurated President Donald Trump that his oil-rich nation will invest at least $600 billion in the US over the next four years.The crown prince told Trump about the investment during a congratulatory phone call on Wednesday evening, per a report from the state-run Saudi Press Agency published on Thursday.According to the report, the two leaders discussed how the US and Saudi Arabia can work together to promote peace and security in the Middle East.Representatives for Trump and Saudi Arabia's foreign ministry did not respond to requests for comment from Business Insider.Trump has long enjoyed a good relationship with the crown prince. Saudi Arabia was the first foreign nation he visited during his first term.When Trump met the crown prince in June 2019, he described him as a "friend of mine " and lauded him for "opening up Saudi Arabia."Deal after dealShortly after being sworn in on Monday, Trump moved quickly, issuing a wave of executive orders covering areas including trade, immigration, and energy.He's also inked deals, both domestically and abroad.On Monday, Trump signed an executive order that would pause the ban on TikTok for 75 days. Trump said while signing the order that the US should own half of TikTok if he's able to halt the ban."I may not do the deal, or I may do the deal. TikTok is worthless, worthless, if I don't approve it," Trump said, adding that the social media platform could be worth $1 trillion.And on Tuesday, Trump announced Stargate, a new joint venture between OpenAI, Oracle, and SoftBank. The president said Stargate plans to invest up to $500 billion in AI infrastructure across the US."Before the end of my first full business day in Washington and the White House, we have already secured nearly $3 trillion of new investments in the United States and probably that's going to be six or seven by the end of the week," Trump said while announcing Stargate on Tuesday, though he did not elaborate on the sources of the new investments.Later, on Wednesday, Trump made an overture to Russian President Vladimir Putin about the Ukraine war. Trump said in a Truth Social post that he was doing Russia a big favor by offering to end the conflict."If we don't make a 'deal,' and soon, I have no other choice but to put high levels of Taxes, Tariffs, and Sanctions on anything being sold by Russia to the United States, and various other participating countries," Trump wrote."We can do it the easy way, or the hard way - and the easy way is always better," Trump added.Saudi Arabia has its own prioritiesIt is unclear how Saudi Arabia's new investment in the US aligns with its economic priorities.In 2016, Saudi Arabia launched its Vision 2030 plan to transform its oil-dependent economy into a more diversified one boosted by tourism and sports. The kingdom has already pumped billions into its economic pivot, with some investments going to the US.But Saudi Arabia's sovereign wealth fund, the Public Investment Fund, said last year that it would focus more on its domestic economy. The PIF is the world's sixth-largest sovereign wealth fund, per the Sovereign Wealth Fund Institute.The PIF's governor, Yasir Al Rumayyan, told delegates at Saudi Arabia's Future Investment Initiative business conference in October that the fund was planning to cut the proportion of foreign investments from 30% to between 18% and 20%."A lot of people would come looking for our money to be invested abroad. But that thing shifted over the years," Al Rumayyan said."So now, we're more focused on the domestic economy and we've been achieving and doing so many big things," he added.