Saudi Arabia could face American retribution over the disappearance of Washington Post columnist Jamal Khashoggi, a top U.S. senator warned Monday.

“I have raised Jamal's disappearance personally with the Saudi ambassador, and while we await more information, know we will respond accordingly to any state that targets journalists abroad,” Senate Foreign Relations Committee Chairman Bob Corker, R-Tenn., tweeted.

Khashoggi, a dissident Saudi Arabian, has been missing since he visited Saudi Arabia’s consulate in Istanbul last week. Turkish investigators have raised suspicions that he was murdered while at the facility, a charge Saudi Arabian Crown Prince Mohammed bin Salman has denied. Turkey is not satisfied by the denial.

“The consulate officials cannot save themselves by simply saying 'he has left'," Turkish President Recep Tayyip Erdogan said Monday. "If he left, you have to prove it with footage. Those who ask Turkish authorities where he is should ask what happened."

Khashoggi’s disappearance comes at a delicate time for U.S. relations with both countries. U.S.-Turkey relations are especially strained, in part due to an authoritarian lurch from Erdogan that includes a crackdown on journalists critical of his government.

“The most significant human rights issues included alleged torture of detainees in official custody; allegations of forced disappearance ... severe restriction of freedoms of expression and media, including imprisonment of scores of journalists, closing media outlets, and criminalization of criticism of government policies or officials,” the State Department’s 2017 report on human rights observed.

The Trump administration is under fire in Congress for cooperating with Saudi Arabia’s military campaign in Yemen, where a civil war has turned into a proxy conflict between the Iran and the leading Arab states of the region. If Khashoggi is confirmed to have been murdered, it would deliver a new blow to U.S. efforts to partner with Saudi Arabia against Iran.

“If this deeply disturbing news report is confirmed, the United States & the civilized world must respond strongly, and I will review all options in Senate,” Florida Republican Sen. Marco Rubio, who sits with Corker on the foreign relations panel, tweeted Sunday.