On Tuesday, President Donald Trump lavished effusive praise on Saudi's de facto ruler, calling him "an incredible man" and a "great guy," and made no mention of human rights concerns in the country.

"I like him a lot. I like him too much," Trump gushed as cameras flashed and the crowd applauded at an investment summit in Riyadh, where the US president kicked off the first major overseas trip of his second term.

The display of affection for a leader with a contentious history mirrored Trump's first term, when he forged an alliance with bin Salman that deepened through years of mutual flattery and dealmaking.

The relationship remains anchored in shared interests: Trump is chasing major economic wins and a revived US role in the region, while bin Salman seeks access to advanced technology, military support and a powerful ally in his push to modernize Saudi Arabia and assert regional leadership.

At the summit, Trump touted a $142 billion defense agreement and a sweeping $600 billion Saudi investment package spanning artificial intelligence, infrastructure and energy.

Trump's ties with the crown prince have sparked criticism from US lawmakers, human rights groups and foreign policy analysts for what they viewed as prioritizing economic interests over human rights.

While bin Salman has denied involvement in journalist Jamal Khashoggi's murder and pointed to reforms such as expanding women's rights as evidence of progress, analysts said these changes were undercut by continued crackdowns on dissent and political freedoms. 

Trump's rapport with bin Salman is far warmer than his White House predecessor's. Yet Biden's relationship with the Saudi leader took a friendlier turn too, evolving from initial harsh criticism to pragmatic cordiality.

Trump's embrace of the Saudis contrasts with a more hesitant initial approach by former president Joe Biden, who had vowed to punish the crown prince after US intelligence found that he ordered the murder of dissident Saudi journalist Jamal Khashoggi in 2018.

Since Khashoggi's gruesome killing, the crown prince has worked aggressively to change Saudi Arabia's image, from easing restrictions on women to diversifying from oil to new areas such as artificial intelligence.

"Saudi Arabia has proved the critics totally wrong," Trump said at an investment forum as the crown prince, at his constant side throughout the day, beamed.

Complimenting the gleaming skyscrapers in the desert capital, Trump said: "The transformation that has occurred under the leadership of King Salman and Crown Prince Muhammad has been truly extraordinary."

"I've never seen anything at that scale happen before," he said.

Trump announced, in response to appeals from the crown prince and Turkey but breaking with ally Israel, that he would ease US sanctions on Syria, ruled by Islamists since the toppling of the iron-fisted Bashar al-Assad in December.

An ultimate prize, pushed both by Trump and Biden, has been to persuade Saudi Arabia, home of Islam's holiest sites, to take the landmark step of recognising Israel.

Trump called normalisation with Israel "my fervent hope and wish, and even my dream".