Saudi Arabia will not extradite suspects in the killing of journalist Jamal Khashoggi in the kingdom’s consulate in Istanbul, its foreign minister said, dismissing a demand by Turkey that 18 people be handed over.

“The individuals are Saudi nationals, they are detained in Saudi Arabia, the investigation is in Saudi Arabia,” Adel Al-Jubeir said Saturday at the Manama Dialogue conference in Bahrain. “They will be prosecuted in Saudi Arabia.”

Turkish President Recep Tayyip Erdogan on Friday called on the kingdom to extradite the suspects Turkish investigators have identified in Khashoggi’s murder as a sign of goodwill. Istanbul’s chief prosecutor has prepared a request for the extradition, state-run Anadolu Agency reported.

The U.S. has already revoked visas for suspects in the killing and will be taking additional measures as the situation is clarified, Secretary of Defense James Mattis said during an earlier address at the same conference.

“The United States does not tolerate this kind of ruthless action to silence Mr. Khashoggi, a journalist, through violence,” he said. “Failure of any one nation to adhere to international norms and the rule of law undermines regional stability when it is needed the most.”

Government Critics

Saudi Arabia, which had initially said the Washington Post columnist left the consulate alive, came closer on Thursday to acknowledging his murder was premeditated as international pressure piles on the kingdom to hold the culprits to account and help locate his body. Khashoggi, a critic of Saudi Crown Prince Mohammed bin Salman’s policies, was last seen on Oct. 2 entering the consulate, where he had gone to pick up a document he needed to remarry.

The Trump administration is facing rising pressure to act against one of its main allies in the region, and President Donald Trump has appeared to be stepping back from giving Prince Mohammed his full support. The U.S. has long been Saudi Arabia’s most important partner and Trump has made the kingdom the centerpiece of his efforts to isolate Iran.

The Saudi-U.S. relationship has weathered storms in the past but it is “ironclad” and much remains at stake, Jubeir told the audience after Mattis’s address. “Otherwise, change would happen so quickly that our heads would spin,” he said.

Six officials have been dismissed as part of the investigation in addition to the 18 who have been detained, Jubeir said, without identifying them. He said he isn’t privy to the details of the investigation and called the media’s coverage of the events “hysterical.”