US President Donald Trump on Thursday said he would travel to Saudi Arabia, probably in the next month and a half, where he is likely to discuss trade, Gaza, the war in Ukraine and Israel normalisation efforts, among other issues.

Trump said the visit is expected to include Riyadh investing more than of $1 trillion in the US, including purchases of military equipment.

"I said, I'll go if you pay $1 trillion, $1 trillion to American companies, [spreading] the purchase over a four-year period, of $1 trillion," he said. "They've agreed to do that, so I'm going to be going there, and I have a great relationship with them."

Earlier on Thursday, Trump's Middle East envoy Steve Witkoff said he would head to the kingdom next week to hold talks on Ukraine and setting up a peace agreement framework that would end the war, three years after Russia's invasion. He said the meeting would take place in Riyadh or Jeddah.

The development comes after Ukrainian President Volodymyr Zelenskyy's visit to the White House last week devolved into a shouting match, with Trump and his Vice President, JD Vance, berating him for not being grateful enough for US assistance.

The visit was cut short and the signing of a critical minerals deal was delayed.

"I think that the President has said that there's a path back, and President Zelenskyy has demonstrated that he's intent on that good-faith path back," Witkoff said. "He's apologised, he said he's grateful, he said that he wants to work towards peace."

Trump, who took office less than two months ago, is intent on advancing his "America First" approach to foreign policy. His administration is working on ending the war on Ukraine and cutting US military assistance to Kyiv.

He said he also wants to bring peace to the Middle East, including through ending the war in Gaza and advancing a normalisation deal between Israel and Saudi Arabia. Trump brokered the signing of the Abraham Accords during his first term and Washington has been working to add Saudi Arabia to the list of signatories.

The former real estate mogul has taken on a unique, business-oriented approach to solving conflicts abroad.

On Ukraine, he proposed an agreement worth billions of dollars that will see the US invest and benefit from the extraction of rare-earth minerals as payback for military aid disbursed during the administration of former president Joe Biden.

And on Gaza, he has proposed expelling about two million Palestinians from the war-ravaged coastal enclave and building a "Riviera of the Middle East" there.

In recent days, his administration has said that the priority is the release of the remaining hostages being held by Hamas and ensuring the group's exclusion from any future government in Gaza.

Trump on Thursday also repeated to reporters, while he was signing executive orders in the Oval Office, that the US would not defend Nato members that do not devote their fair share of spending to defence.

"If they don't pay, I'm not going to defend them," he said.

Trump and many of his Republican allies have frequently questioned why Washington should continue in its role as the main funder of Nato and has accused other nations of taking advantage of the US. He has also said that Europe should do more to fund Ukraine.