President Donald Trump said Monday morning that he would send Secretary of State Mike Pompeo "immediately" to meet with the Saudi king as the international outcry continued to grow over missing journalist Jamal Khashoggi.
The president also said King Salman denied knowledge of anything regarding the writer's fate. "His denial to me could not have been stronger," Trump told reporters later Monday morning. The president also suggested that "rogue killers" might have murdered Khashoggi, a Saudi national and critic of the royal family who was living in the U.S. under self-imposed exile.
Trump said Pompeo would be departing for the kingdom on Monday morning. The State Department confirmed the top diplomat would be leaving Monday.
"At the request of President Trump, Secretary of State Pompeo will travel to Riyadh, Saudi Arabia today. The President has called for a prompt and open investigation into the disappearance of Washington Post journalist Jamal Khashoggi," the department said in a statement.
The White House didn't immediately respond to CNBC's request for further comment on the president's tweet. In a readout of the king's call with Trump, the Saudi government said the president "praised the joint Saudi-Turkish cooperation in the investigation into the disappearance of Jamal bin Ahmed Khashoggi and the keenness of the Kingdom's leadership to clarify all relevant facts."
Saudi Arabia is the world's biggest oil exporter, and a standoff with the royal family could create turbulence for the global economy, particularly in crude markets.
The Trump administration is relying on Saudi Arabia to pump more oil to compensate for the loss of Iranian supplies due to U.S. sanctions on Iran, OPEC's third largest crude producer. The sanctions are poised to remove about 1 million barrels a day from the market, or roughly 1 percent of global oil demand.
Oil prices initially rose on Monday after Saudi Arabia vowed on Sunday to retaliate against any sanctions or other measures taken against the kingdom. The statement raises concerns that Saudi Arabia could respond to international punishment by allowing oil prices to drift higher.
Crude futures turned negative following Trump's tweet and his comment regarding "rogue killers."
Trump's tweet came after King Salman ordered an investigation into Khashoggi's disappearance. The journalist, a critic of the Saudi royal family who wrote columns for The Washington Post, was last seen Oct. 2, when he entered the Saudi consulate in Istanbul. While Salman is the official head of state, Crown Prince Mohammed bin Salman has exerted extraordinary influence over the country's defense, intelligence and economic policy and strategy.
The Turkish government believes Khashoggi was murdered. Turkey has reportedly informed the U.S. that it has video and audio evidence showing the journalist was killed inside the consulate.
Saudi Arabia denies wrongdoing, a point Trump stressed in his Monday morning tweet. "Just spoke to the King of Saudi Arabia who denies any knowledge of whatever may have happened 'to our Saudi Arabian citizen,'" Trump wrote, noting again that Khashoggi is not an American.
Khashoggi's disappearance and suspected murder have triggered a worldwide wave of outrage. Prominent bankers, such as JP Morgan CEO Jamie Dimon, and media organizations have been dropping out of an investment conference scheduled for later this month in Riyadh.
Treasury Secretary Steven Mnuchin told CNBC last week that, at the moment, he still planned to go. A Treasury representative said Monday: "We will be evaluating the information that comes out this week."
Senators in the U.S., led by Republicans Lindsey Graham and Bob Corker, have triggered a Trump administration investigation into the journalist's fate that could end up in sanctions. The president himself has warned of "severe consequences" if indeed it does turn out that Saudi Arabia's government had Khashoggi killed.
Speaking to reporters Monday morning, however, Trump emphasized in an impromptu press gathering Monday morning that the Saudi king strongly denied having to do with Khashoggi's vanishing – while appearing to acknowledge that the journalist was killed.
"It sounded to me like maybe these could have been rogue killers," Trump said.
-CNBC's Kevin Breuninger and Matthew Belvedere contributed to this article.