WASHINGTON — After defending U.S. arms sales to Saudi Arabia over the weekend, President Donald Trump on Monday touted the denials of the Saudi royal family in disappearance of journalist Jamal Khashoggi and suggested “rogue killers” could be responsible, rather than the Saudi government.

Following a call Monday morning between Trump and Saudi King Salman bin Abdulaziz Al Saud, the president said he was sending Secretary of State Mike Pompeo to Saudi Arabia “immediately,” and possibly Turkey, “to get to the bottom of” the Khashoggi matter. Trump said it appeared both the king and Crown Prince Mohammed bin Salman “had no knowledge,” based on the call.

“We are going to leave nothing uncovered. With that being said, the king firmly denies any knowledge of it,” Trump told reporters outside the White House. “He didn’t really know, maybe — I don’t want to get into his mind — but it sounded to me like maybe it could have been rogue killers, who knows? We’re going to try get to the bottom of it very soon, but his was a flat denial.”

The statement came as international concern grew over the writer who vanished on a visit to the Saudi Consulate in Istanbul over a week ago. American lawmakers have threatened punitive action against the Saudis, and Germany, France and Britain jointly called for a “credible investigation” into Khashoggi’s disappearance.

Turkish officials have said they fear a Saudi hit team killed and dismembered Khashoggi, who wrote critically of Saudi Crown Prince Mohammed bin Salman. The kingdom has called such allegations “baseless” but has not offered any evidence Khashoggi ever left the consulate.

Sen. Bernie Sanders, Vt.-I, on Monday, announced he would reintroduce a resolution to end U.S. military aid to the Saudi-led coalition fighting in Yemen, citing Khashoggi’s disappearance “and likely assassination.” That support includes aerial refueling of coalition aircraft and arms sales.

Sanders said the resolution, when Congress returns from recess next month, would “give the Senate another opportunity to end U.S. support for this catastrophe, to reassert congressional authority over matters of war, and to show the Saudi government that they do not have a blank check from the United States to continue human rights violations.”

Earlier this year, Sanders led a bipartisan group of lawmakers in a resolution which invoked the 1973 War Powers Act to compel the Trump administration to drop U.S. support. The resolution was tabled, 55-44.

Citing the $110 billion worth of weapons the Trump administration pledged to sell Riyadh over the next decade, Trump has repeatedly said that halting arms sales to Saudi Arabia is off the table. He’s argued Riyadh could turn to Russia, China and other foreign suppliers.

In an interview with “60 Minutes," Trump said that “we would be very upset and angry” if the crown prince were to have ordered Khashoggi’s murder, and he vowed “severe punishment.” He restated his opposition to halting U.S.-Saudi arms deals.

“I tell you what I don’t want to do. Boeing, Lockheed, Raytheon, all these — I don’t want to hurt jobs,” Trump said.

U.S. lawmakers have variously called on the administration to investigate under the 2016 Global Magnitsky Act — which could trigger sanctions — to drop U.S. military support for the Saudi-led campaign in Yemen and halt U.S. arms sales to Riyadh, which represents a major market for U.S. defense firms.

Sen. Robert Menendez, the top Democrat on the Foreign Relations Committee, has for months blocked the sale of tens of thousands of Raytheon-made precision-guided munitions kits, citing concerns over civilian casualties caused by the Saudi-led coalition fighting in Yemen.

The Senate’s No. 2 Democrat, Sen. Richard Durbin of Illinois, said on social media Monday afternoon: “Since Saudi arms are being used to ravage Yemen and they are apparently complicit in the disappearance of Mr. Khashoggi, I cannot support President Trump’s proposed arms sale.”

Durbin, who is also the senior Democrat on the Senate Appropriations Defense Subcommittee, told CNN earlier in the day: “We ought to get out of the war in Yemen.”

“The United States government is backing and helping the Saudis in the war in Yemen that is killing millions of people by warfare and famine,” Durbin said. “We ought to be out of that tomorrow. We ought to make sure that we know the export of this Wahabi extremism that they've been engaged in for decades is unacceptable.”

Durbin stopped short of saying the U.S. ought to stop arms sales to Riyadh, but he was willing to accept if Riyadh halted them in retaliation — so long as the U.S. sends a strong signal that Saudi Arabia’s alleged involvement in Khashoggi’s disappearance would be unacceptable.

“If you’re not going to stop the arms sales, what will you do to the Saudis so that they understand tomorrow that what they’ve done is absolutely unacceptable?” Durbin said. “If it is just a strong letter in some diplomatic channel, absolutely unacceptable."

The Associated Press contributed to this report.