"We are very disappointed to see what's going on. We don't like it. We don't like it at all. And we're going to get to the bottom of it," Trump said at a bill signing event Wednesday.
A senior Turkish official told The New York Times that Khashoggi was murdered and gruesomely dismembered with a bone saw in the Saudi Consulate in Istanbul. Saudi Arabia, however, insists that Khashoggi left the consulate shortly after he arrived.
Khashoggi, a Saudi journalist who had criticized the kingdom's royal family and exiled himself to the United States, entered the consulate in Turkey on Oct. 2 and has not been seen outside it since, the Post reported.
White House press secretary Sarah Huckabee Sanders said in a statement that national security advisor John Bolton and Trump's senior advisor and son-in-law, Jared Kushner, had spoken about Khashoggi on Tuesday with Saudi Crown Prince Mohammed Bin Salman. Secretary of State Mike Pompeo followed up with the crown prince afterward.
In both phone calls, the U.S. officials asked for more details and for the Saudi government's transparency in its investigation, Sanders said. Her statement, posted below, made no mention of any action or acknowledgement on the Saudi side.
White House National Security Advisor, Ambassador John Bolton and White House Senior Advisor, Jared Kushner spoke to Saudi Arabian Crown Prince Mohammed Bin Salman yesterday about the missing Washington Post journalist. Secretary of State Mike Pompeo then had a follow up call with the Crown Prince to reiterate the United States request for information. In both calls they asked for more details and for the Saudi government to be transparent in the investigation process. We will continue to monitor this situation and provide updates as available.
Graham on Wednesday noted that he has "been very supportive of Saudi Arabia" in the past. As chair of the subcommittee on appropriations handling U.S. foreign assistance, he had voted in favor of a $500 million arms sale to Saudi Arabia in 2017. He has also called the kingdom "a valuable partner in the war on terror."
"If you want to lose Saudi Arabia as an ally, be careful what you wish for," Graham said in 2016.
Graham has met with the Saudi ambassador before, Kevin Bishop, a spokesman for the senator, told CNBC in an email.
"If it did happen there would be hell to pay," Graham said. "If they're this brazen it shows contempt. Contempt for everything we stand for, contempt for the relationship."
Shortly after Graham's remarks, Trump said in the Oval Office that he has already spoken with high-level Saudi officials about Khashoggi. He added that Khashoggi's fiancee, Hatice Cengiz, has been in contact with his administration and may come to the White House.
Other lawmakers have become involved in the inquiries about Khashoggi.
"We have intelligence that reports to Saudi involvement. Obviously, if that's the case, they need to obviously follow up. This is serious," said Sen. Jeff Flake, R-Ariz., on Wednesday. Flake said that he planned to view information about Khashoggi's disappearance in a secure room known as a "Sensitive Compartmented Information Facility."
Sen. Bob Corker, chairman of the Senate Foreign Relations Committee, said in a tweet Monday that he had spoken with the Saudi ambassador.