The CIA believes that Saudi Crown Prince Mohammed bin Salman ordered the murder of journalist Jamal Khashoggi, according to US media reports.
Sources close to the agency said it had assessed the evidence in detail.
It is understood there is no “smoking gun” but US officials think such an operation would need the prince’s approval.
Saudi Arabia has called the claim false and insisted that the crown prince knew nothing about plans for the killing.
It says Khashoggi was killed as a result of a “rogue operation”.
US President Donald Trump has spoken to CIA Director Gina Haspel and Secretary of State Mike Pompeo about the CIA’s assessment of the Khashoggi murder, the White House says.
Press secretary Sarah Sanders gave no details but said Mr Trump had confidence in the CIA.
Before the briefing, President Trump stressed the importance of Saudi Arabia to the US, as he has done since news of Khashoggi’s killing emerged.
“They have been a truly spectacular ally in terms of jobs and economic development,” he said. “I have to take a lot of things into consideration.”
While there has been widespread international condemnation of Khashoggi’s murder there has been little in the way of substantial action.
The journalist was killed after entering the Saudi consulate in Istanbul on 2 October to obtain a marriage document. His body has not been found.
Turkey also insists the order to kill him came from the highest levels.