Updated at 11:54 p.m. ET
Nearly two weeks since Jamal Khashoggi vanished in Istanbul, the shadow of the Saudi journalist's disappearance continues to loom ever larger. Now, President Trump is threatening "severe punishment" for Saudi Arabia if suspicions of Khashoggi's murder are confirmed — and Saudis have vowed to retaliate in kind.
"The Kingdom also affirms that if it receives any action, it will respond with greater action," Saudi Arabia's state-run news agency said Sunday, ominously noting that the country plays "an influential and vital role in the global economy."
Citing an "official source," the Saudi Press Agency added that Riyadh "affirms its total rejection of any threats and attempts to undermine it." Rather, if Saudis face "political pressures" such as accusations or sanctions, "the outcome of these weak endeavors, like their predecessors, is a demise."
The Saudi Embassy in Washington, D.C., later sought to "clarify" those threats on Twitter, noting that "the Kingdom of Saudi Arabia extends it appreciation to all, including the US administration, for refraining from jumping to conclusions on the ongoing investigation."
The comments Sunday follow Trump's toughest comments yet about the simmering international controversy. Speaking with CBS's 60 Minutes, the president said that "nobody knows yet" whether the Saudi government ordered the killing of Khashoggi, a frequent critic, as Turkish officials reportedly allege.
"It's being investigated, it's being looked at very, very strongly," Trump said. "And we would be very upset and angry if that were the case."
Still, he was careful to hedge his language — as he has been largely since Khashoggi vanished after the journalist's visit to the Saudi consulate in Istanbul. His administration has been on friendly terms with the Gulf regional power since taking office, supporting the Saudi-led airstrike campaign in Yemen and brokering an arms deal that could be worth $110 billion over the next decade.
During a news conference in the Oval Office on Saturday, Trump responded to a question about his response to the Khashoggi controversy by touting the economic benefits of the weapons sale.
"If they don't buy it from us, they're going to buy it from Russia or they're going to buy it from China or they're going to buy it from other countries," he said. "From the standpoint of jobs, economic development, a lot of other reasons, I would like to do something where we could maybe look at other things [than canceling the deal]."
Nevertheless, the Saudi Stock Exchange plummeted about 7 percent at one point Sunday on fears of economic fallout from the diplomatic dispute, before recovering some of its losses later in the day.
So far, administration officials have also expressed reluctance to canceling participation in Saudi Arabia's signature economic forum, the Future Investment Initiative. A wide array of global business leaders — including World Bank President Jim Yong Kim and Virgin founder Richard Branson — has pulled out of the conference later the month. At the moment Treasury Secretary Steven Mnuchin plans to keep his own plans to attend — though Secretary of State Mike Pompeo says they're evaluating the situation closely.
U.S. lawmakers, for their part, have come out more strongly. A bipartisan group of nearly two dozen senators have called for an investigation into Khashoggi's disappearance, and some have suggested they would be willing to block the Saudi arms deal if more damaging details come to light.
"I don't think that we should continue with business as usual until we know exactly what happened here, because what we do know is this: He walked into that consulate and he never came out," Sen. Marco Rubio, R-Fla., told CNN on Sunday. "So the only two things that could have happened is, he's alive and somehow still in there, or he's dead and the Saudis are the ones who did it. There's no other explanation for it."
And Rubio said that no U.S. government officials should be attending the Saudi conference until they get some official answers about what happened.
"No matter how important they may be to our Iranian strategy," he added, "our ability to be a voice for human rights — and to go after regimes like [Syrian President Bashar] Assad, like [Russian President Vladimir] Putin, like what China does, like what [President Nicolas] Maduro does in Venezuela — all of that is undermined and compromised if we are not willing to confront something as atrocious as what's allegedly happened here."
European leaders followed in demanding answers from the Saudi government, in a joint statement on Sunday. Three foreign ministers from the U.K., France and Germany called for "a credible investigation to establish the truth about what happened [to Khashoggi]," and for those responsible for his disappearance to be held accountable.
"We encourage joint Saudi-Turkish efforts in that regard, and expect the Saudi Government to provide a complete and detailed response," said British Foreign Secretary Jeremy Hunt, French Foreign Minister Jean-Yves Le Drian and German Foreign Minister Heiko Maas — a message they said they issued directly to Saudi officials.
NPR's Emma Bowman contributed to this story.