Claims by Turkish officials that investigators have found evidence that Jamal Khashoggi was killed inside the Saudi consulate in Istanbul have not completely derailed US efforts to ease the biggest diplomatic crisis between Saudi Arabia and western interests for generations, but it has left the administration struggling for options.

The White House knows it will be straining credulity with its supporters if, as Donald Trump has suggested, it were to accept Riyadh’s claim that Khashoggi’s presumed killing was the result of a rogue operation that went wrong.

Much will depend in the critical next few days on how the Turkish president, Recep Tayyip Erdoğan, handles the crisis. He could remain on the offensive, leaving Saudi Arabia, and potentially the US administration, squirming in the court of world opinion, or he could use the Saudis’ miscalculation to bargain to Turkey’s advantage.

Jamal Khashoggi affair is proving a critical test for US diplomacy Read more

Erdoğan has two outstanding grievances with the US: its refusal to extradite the Turkish cleric Fethullah Gülen, whom he sees as the chief conspirator behind a failed military coup in 2016; and its continued support for Kurdish YPG fighters in northern Syria.

Ankara’s demands are more complex in relation to Saudi Arabia, but the Turkish economy, struggling under the weight of a depleted currency and spiralling inflation, could certainly benefit from Saudi Arabian investment.

It is surely a sign of the severity of the crisis, and the huge commercial investments at stake, that the US secretary of state, Mike Pompeo, made a 12-hour journey to Riyadh for a 15-minute meeting with King Salman, followed by a longer and more serious meeting with the crown prince, Mohammed bin Salman. If Washington has hatched a plan to try to save the Saudi royal family from international pariah status by running the argument that rogue agents interrogated Khashoggi to the point of death, as has been reported in the US media, it would have been discussed at this second meeting.

But even the admission of a rogue operation required Saudi Arabia to change its position. For two weeks, the kingdom either denied all knowledge of Khashoggi’s death, or suggested the claims were the work of a Qatari-led conspiracy designed to isolate Saudi Arabia and promote the Muslim Brotherhood.

Saudi-friendly sources repeatedly claimed that Khashoggi left the consulate on 2 October and that it was up to Turkey to locate him.

Yet there now seems to be no attempt to deny his death, and there are few knowledgable of Saudi court politics who really believe such an operation could have been sanctioned by anyone but the crown prince. The US senator Lindsey Graham, a Republican close to Trump and a past defender of Saudi Arabia, on Thursday blamed the crown prince and described him as a “wrecking ball”.

“I’ve been their biggest defender on the floor of the United States Senate,” he told Fox News. “This guy is a wrecking ball. He had this guy murdered in a consulate in Turkey and to expect me to ignore it. I feel used and abused.”

The UK foreign secretary, Jeremy Hunt, will not use the same vitriolic language but has little doubt over what has occurred. The Turkish foreign minister, Mevlüt Çavuşoğlu, will have briefed him on the Turkish evidence behind claims that Saudi intelligence agents, including anaesthetists and some carrying hacksaws and other devices, arrived in the country to conduct a violent interrogation intended to permanently silence the crown prince’s most persistent and eloquent critic.

Profile Who was Jamal Khashoggi? Show Hide Jamal Khashoggi was one of the Arab world’s most prominent journalists and commentators. He was an outspoken critic of Saudi Arabia who dared to defy Crown Prince Mohammed bin Salman. While living in Saudi Arabia, Khashoggi was told to stop writing or posting on Twitter, where he had more than 1.6 million followers. He moved to the US in June 2017, where he continued to comment on his country both in print and on television. He wrote columns for the Washington Post and the Guardian.

His message struck a nuanced tone in the US, where he tried to acknowledge the reforms undertaken by Bin Salman while also highlighting the flaws. Khashoggi previously had close links with the Saudi royal family, including having served as a media aide to Prince Turki al-Faisal, when the latter was director general of the Saudi intelligence agency. He was also a former editor of the Saudi newspaper al-Watan and had worked with Prince Alwaleed bin Talal, a grandson of the first Saudi king. Khashoggi was murdered in the Saudi Arabian consulate in Istanbul in October 2018. Photograph: Virginia Mayo/AP

It has always been the source of the crown prince’s strength that little in government happens without his permission. In this episode his unbridled authority may prove his undoing.

The challenge for the Americans is whether, in the absence of definitive documentary evidence, the White House can brazen it out and persist with the rogue operation theory. That will involve complex judgments about the security of the crown prince as heir to the throne, and the fact that his many internal enemies will be circling.