The controversy over the 2018 killing of Khashoggi, a Washington Post columnist and US-based critic of the Saudi leadership, flared again in the Oval Office in front of cameras as the kingdom's de facto ruler made his first White House visit in more than seven years, seeking to further rehabilitate his global image tarnished by the incident.
US intelligence agencies concluded that bin Salman approved the capture or killing of Khashoggi at the Saudi consulate in Istanbul. The crown prince denied ordering the operation but acknowledged responsibility as the kingdom's de facto ruler.
"A lot of people didn't like that gentleman that you're talking about, whether you like him or didn't like him," Trump told reporters in the Oval Office with bin Salman sitting beside him.
"Things happened, but he knew nothing about it, and we can leave it at that," he said on Tuesday.
Bin Salman said it had been "painful" to hear about Khashoggi's death but that his government "did all the right steps of investigation".
"We've improved our system to be sure that nothing happened like that. And it's painful and it's a huge mistake," he told reporters.
Trump, who chided the reporter who asked the Khashoggi question "to embarrass our guest", also praised the crown prince for doing an "incredible" job on human rights but did not elaborate.
Trump's treatment of bin Salman prompted a rebuke from Khashoggi's widow.
"There is no justification to murder my husband. While Jamal was a good transparent and brave man many people may not have agreed with his opinions and desire for freedom of the press," Hanan Elatr Khashoggi wrote on X, urging bin Salman to meet with her.
Bin Salman has been strongly criticised by human rights groups not only for the Khashoggi killing but for his crackdown on dissent at home. But the crown prince has also unleashed major social reforms that have swept away some austere social codes.
At the start of his visit, the crown prince was greeted with a lavish display of pomp and ceremony presided over by Trump on the South Lawn, complete with a military honour guard, a cannon salute and a flyover by US warplanes.
The meeting underscores a key relationship - between the world's biggest economy and the top oil exporter - that Trump has made a high priority in his second term as the international uproar around the killing of Khashoggi, a Saudi insider-turned-critic, has gradually faded.
The warm welcome for bin Salman in Washington marks a high point for the US-Saudi ties, which have suffered because of Khashoggi's murder.
Sitting next to Trump, bin Salman promised to increase his country's US investment to $US1 trillion ($A1.5 trillion) from a $US600 billion ($A922 billion) pledge he made when Trump visited Saudi Arabia in May. But he offered no details or timetable.
A $US1 trillion investment in the US would be difficult for Saudi Arabia to pull together given its heavy spending on an already-ambitious series of massive projects at home, including futuristic megacities that have gone over budget and faced delays and stadiums for the 2034 World Cup.
