The alleged murder and dismemberment of Saudi dissident Jamal Khashoggi in Turkey in an operation ordered by the top level of the kingdom's royal court could have a "devastating" effect on U.S.-Saudi relations, according to a key Trump ally.

“If it's proven to be true, it would be devastating to the relationship,” Sen. Lindsey Graham, R-S.C., replied when asked if the case might threaten the U.S.-Saudi strategic partnership. “Yes, everything would be changed.”

President Trump has looked to Saudi Arabia as a Sunni counter to Iran's regional aggression and Shia expansionism — a partnership that builds on the monarchy’s traditional role as an anchor of U.S. interests in the Middle East. In addition, Saudi Arabia has been supportive of pressuring Palestinians to enter into peace deal with Israel.

Iran hawks, such as Graham, and other prominent national security officials have applauded that effort, but the disappearance of Khashoggi, a former Saudi court insider turned critic and Washington Post columnist, has caused an outcry among U.S. leaders that could upturn the delicate balance of U.S. policy in the Mideast.

Khashoggi entered the Saudi consulate in Istanbul after lunchtime last Tuesday, the day before his wedding, seeking documents necessary to get married. His fiancee, Hatice Cengiz, waited outside. "She was still waiting there after midnight,” the New York Times reported.

Saudi officials at the consulate gave their Turkish employees the day off, according to local reports, leaving no foreign witnesses to observe what happened next. Turkey believes that Khashoggi was murdered and dismembered by a 15-person assassination squad sent into the country just for that purpose, according to reports. “It is like ‘Pulp Fiction,’” a senior Turkish official told the Times.

The grisly tale has lawmakers comparing Saudi Arabia’s alleged crime to some of Iran’s most dramatic rogue actions. “It's high visibility,” Wisconsin Sen. Ron Johnson, another senior Republican on the Foreign Relations panel, told the Washington Examiner. “Just like we've seen in other high-visibility [cases] — Iranian operatives trying to murder the Saudi ambassador in Washington, D.C., these things take on a very large role in terms of peoples' opinion of how to react to a particular nation. It's horrific, what's being reported, and we need to find out what happened.”

Saudi Crown Prince Mohammad Bin Salman, or MBS as the royal is known, has denied any role in Khashoggi's disappearance, but Saudi officials haven’t been able to prove that Khashoggi left their custody. A Saudi diplomat told Senate Foreign Relations Chairman Bob Corker, R-Tenn., that their security cameras “only live-stream” due to a malfunction. “That was pretty hard for me to believe, and I shared that with him,” Corker told reporters Tuesday evening. "It feels very much like some nefarious activity has occurred by them.”

Corker predicted “tangible repercussions” for Saudi Arabia, if the murder is confirmed, but lawmakers have kept the details of that response close to the vest. A bipartisan minority of senators, quite apart from the Khashoggi case, have called for years for a cut in foreign military sales to the oil-rich country. New Jersey Sen. Bob Menendez, the top Foreign Relations Democrat known for his hawkish views on Iran, promised that Saudi Arabia’s alliance with the United States would be no protection in this case.

“The good trend is the cooperation and work that we're all doing together with regard to the broader strategic threat in the region, which in my view clearly is Iran,” Senate Armed Services Committee member Dan Sullivan, R-Alaska, told the Washington Examiner. "So, we’re trending in a good direction, but, this could put that off the rails."

Underlining that potential derailment, a bipartisan group of nearly two dozen senators initiated the process by which Trump could impose sanctions on Saudi Arabian officials involved in the Khashoggi case.

“Our expectation is that in making your determination you will consider any relevant information, including with respect to the highest ranking officials in the Government of Saudi Arabia,” Corker and Menendez wrote in a letter signed by 20 of their colleagues.

The letter — which was also signed by Graham and Democratic Sen. Patrick Leahy of Vermont, who oversee the State Department’s budget on the appropriations committee — starts a 120-day clock for deciding whether to impose sanctions. It’s a major development for an American foreign policy consensus that has nurtured the U.S.-Saudi Arabia relationship for decades in the face of persistent worries about the Wahhabi monarchy’s role in financing terrorism and other human rights abuses.

MBS has tried to allay those fears through a “charm offensive” of domestic reforms implemented with one eye on Western powers. He ended a long-standing ban on female drivers in Saudi Arabia, for instance, and undermined the authority of Muslim clerics in the country through arrests of hard-liners and the decision to strip religious police of there power to make arrests for violations of Islamic law.

“The expectations were heightened, making something like this seem that much more dramatic,” Jonathan Schanzer, a vice president of the Foundation for Defense of Democracies, told the Washington Examiner.

American officials have a sharp interest in responding to the Khashoggi case, given that he had lived in the United States and worked for an American media outlet.

“The idea of an extrajudicial rendition is unsettling," Schanzer said. “It's something that cannot be condoned and really has to be addressed, if the United States is to ensure that this doesn't happen again. The Russians are watching. The North Koreans are watching. The Chinese are watching. The Turks are watching, for that matter.”

That warning highlights one of the troubling paradoxes of the Khashoggi case. Turkish President Recep Tayyip Erdogan, for all his demands that Saudi Arabia explain what happened, has overseen one of the world’s most aggressive media campaign since a failed coup attempt in 2016. He defends mass arrests by accusing journalists of complicity in terrorism.

Turkish officials more recently have talked publicly about carrying out intelligence operations in the United States. Erdogan alleges that Trump’s team is sheltering the Pennsylvania-based cleric, Fetullah Gulen, who he blames for orchestrating the attempted coup. Former Trump national security advisory Michael Flynn, famously, was accused of attending a meeting in which Turkish officials lobbied for Gulen’s kidnapping.

“The fact that they've been accused of doing this themselves obviously puts all of this in a weird context,” Schanzer said. “It's an incredibly odd moment. Here you have the Turks, that are the No. 1 jailers of journalists in the world and have been accused of these extrajudicial renditions of Gulenists, and here they are making these allegations. You can’t make this stuff up.”

He added that there were some question marks over the Turkish account. Erdogan has clashed with the oil-rich monarchy of late, most notably by opposing a Saudi-led effort to isolate Qatar.

“The Turks have a notoriously sketchy intelligence service. More broadly, the Turks have sided with the Qataris in the Gulf spat, which would give them a reason to target the Saudis. So even though the evidence does appear to be stacked up against Saudi Arabia, there are lingering concerns.”

Khashoggi’s disappearance is another blow to the self-cultivated image of MBS as a reformer, in a Senate already frustrated by Saudi Arabia’s responsibility for civilian casualties in Yemen’s civil war.

“We can't let anything become a carte blanche at the end of the day; the day we do that, then we're hostage,” Menendez told reporters.