Saudi King Salman presented President Trump with the highest civilian honor during the president’s visit to the kingdom in May 2017. (Evan Vucci/AP)

When the White House finally questioned Saudi Arabia about a week’s worth of reports that its agents had kidnapped, and possibly killed, a dissident Saudi journalist in Istanbul, the contact was not made with King Salman or the foreign minister.

Instead, the call Tuesday from presidential aide and son-in-law Jared Kushner and national security adviser John Bolton went to Crown Prince Mohammed bin Salman, the heir apparent and power behind his father’s throne.

Mohammed has been the go-to Saudi since the administration took office, key to President Trump’s goal of partnering with Riyadh to bring Iran to heel, achieve an Israeli-friendly peace settlement with the Palestinians and sell billions worth of U.S. weapons along the way.

But the disappearance of Jamal Khashoggi, a U.S. resident last seen entering the Saudi consulate in Istanbul on Oct. 2, has thrown a wrench in those plans. Amid increasingly loud and credible reports that Khashoggi is dead, Saudi officials have apparently refused to cooperate in a Turkish investigation or provide its U.S. ally with information.

Already, Congress has moved to take the lead. Top foreign policy lawmakers in the Senate called on Trump on Wednesday to sanction “any foreign person responsible for the violation of Mr. Khashoggi,” including the “highest-ranking officials in the Government of Saudi Arabia,” under the Global Magnitsky Act, which allows the United States to target specific government officials involved in human rights abuses.

The letter to Trump was signed by Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.) and the ranking Democrat, Sen. Robert Menendez (N.J.), along with nine Republican senators and an equal number of Democrats. The act gives the president 120 days to determine whether sanctions are warranted.

At their request, members of the House Intelligence Com­mittee were also briefed by the administration on the Khashoggi matter.

“If the horrific allegations of what occurred are accurate,” the committee’s ranking Democrat, Rep. Adam B. Schiff (Calif.), said, “this episode must dramatically recast the U.S.-Saudi relationship.”

Trump, whose earlier remarks on Khashoggi had been limited to a brief expression of concern, told reporters Wednesday that he was “not happy” about what he called “a bad situation.” He said the White House had spoken to Saudi Arabia at “the highest levels,” a news flash that led to the release of an official statement acknowledging the Kushner-Bolton call with the Saudi crown prince the day before.

“We cannot let this happen to reporters, to anyone,” Trump said, adding that the administration was also in contact with Khashoggi’s Turkish fiancee, Hatice Cengiz, who had stood outside the Saudi Consulate in Istanbul while he went in to pick up paperwork for their marriage, waiting in vain for his return.

“We want to bring her to the White House,” Trump said.

The subsequent statement from White House press secretary Sarah Huckabee Sanders said there was also a follow-up call to MBS, as the crown prince is widely known, from Secretary of State Mike Pompeo. But Sanders provided little substantive information.

“In both calls, they asked for more details and for the Saudi government to be transparent in the investigation process,” she said. “We will continue to monitor this situation and provide updates as available.”

At the State Department, dep­uty spokesman Robert Palladino declined to characterize Pompeo’s call with MBS, referring to it as “private diplomatic conversations.”

“I would say that the United States government wants to understand what is going on,” he said, “and to express the importance of receiving a full accounting. And understanding in a very transparent and conclusive way what has transpired. We’d like to get to the bottom of this.”

For those who never trusted Mohammed and bemoaned the president’s appointment of Kushner, a diplomatic naif, as his primary U.S. interlocutor, the Khashoggi incident is already a policy disaster even before official conclusions have been reached.

“In a way, I understand the logic behind putting Jared Kushner forward,” Stephen J. Hadley, national security adviser to former president George W. Bush, said in a Washington panel discussion this year. Both are sons of leaders, he said, and in the “informal way New York real estate works, [it is the] informal way politics works among families in the region.”

But “it doesn’t really work” in this case, Hadley said. “You need someone there who is a steady hand, who understands the region.”

U.S. intelligence officials have long regarded MBS with skepticism and trepidation. The prince, 33, rose to power in a palace coup last year that displaced his older cousin Mohammed bin Nayef, whom the CIA regarded as a fellow warrior in the long U.S. fight against al-Qaeda and other violent extremists.

Diplomatic, defense and intelligence officials became even more wary as they puzzled over private talks between Mohammed and Kushner, 37, held during late-night telephone conversations and several visits to each other’s capital.

MBS, said one senior intelligence official, has perfected an “elevator pitch” on what he thinks are quick fixes to complex problems in the Middle East, persuading the administration that the answer to all its problems lay in confronting and isolating Iran — a view that found quick agreement in the White House. This official and others spoke on the condition of anonymity about the sensitive relationship.

The administration has stood by the crown prince as he has waged a war in Yemen that has killed thousands of civilians and led to one of the deepest foreign policy breaches between Trump and lawmakers from both parties who have tried to curtail U.S. military assistance to the Saudis.

Trump initially supported the Saudis and the United Arab Emirates last year when they broke relations with neighboring Qatar, charging support for terrorism, only to reverse himself months later after objections from Defense Secretary Jim Mattis and then-Secretary of State Rex Tillerson.

Instead of the praise the White House has lavished on MBS and his father, “the administration should treat the crown prince and the foreign minister,” former Saudi ambassador to the United States Adel al-Jubeir, “as international pariahs,” said Bruce Riedel, who served more than 30 years in the CIA and is the author of “Kings and Presidents,” a book about U.S.-Saudi relations since the Franklin D. Roosevelt administration.

“Using a diplomatic facility for kidnapping and murder is tantamount to war crimes and should result in being ostracized from the global community,” Riedel said. “Trump won’t do it, but he should.”

Many Saudi experts have speculated that Kushner’s affinity for MBS is a generational one, as the dynamic crown prince has taken steps toward social and economic modernization of the deeply conservative kingdom.

Saudi antipathy toward Iran, and common cause with the administration in seeking to stem its activities, is genuine. Despite its concern over the way the Saudis are conducting the war in Yemen, the Pentagon is committed to a regional security alliance with the Saudis.

But the Trump administration is mistaken if it believes that what MBS does inside Saudi Arabia or for domestic reasons is designed to solidify foreign relations or in response to U.S. entreaties, said Princeton University professor Bernard Heykal, an authority on Saudi Arabia and the region.

“Nothing that MBS is doing is for pleasing the West,” Heykal said on the panel with Hadley. “He is doing it because he has to do it for himself” and Saudi Arabia. “It just so happens,” he said, that much of Saudi policy “corresponds to [U.S.] interest, and our desire to remain powerful and important in that region.”

Shane Harris, Carol Morello and Anne Gearan contributed to this report.