THREE GOVERNMENTS now bear inescapable responsibility to act on the disappearance of Jamal Khashoggi, the renowned Saudi journalist and commentator for The Post, who vanished after entering Saudi Arabia’s consulate in Istanbul last Tuesday. For more than a year, Mr. Khashoggi called attention in his columns to the increasingly authoritarian behavior of the Saudi crown prince, Mohammed bin Salman. On Saturday, unnamed sources in Turkey said Turkish investigators believe that Mr. Khashoggi was murdered inside the consulate.

If true, this is a horrific crime, the assassination of a journalist in his own country’s consulate on foreign soil — something without precedent in modern times. So far, we have no proof. Turkish President Recep Tayyip Erdogan on Sunday said the events are “very, very upsetting,” but he stopped short of confirming reports of a murder. Saudi Arabia continues to insist that Mr. Khashoggi left the consulate after a brief visit Tuesday, but it has provided no evidence to back that up. Amid the conflicting statements, an ominous timeline emerged in some of the accounts. Mr. Khashoggi went to the consulate Sept. 28 in a first attempt to take care of some routine paperwork and was told to come back the following week. Then 15 Saudi officials entered Istanbul, “specifically for the murder,” according to sources quoted by The Post’s Kareem Fahim. Mr. Khashoggi entered the consulate again last Tuesday and did not come out.

Saudi Arabia must immediately answer: Who were these 15 officials? What happened, precisely, inside the consulate? The contrived “visit” inside the consulate arranged for Reuters journalists on Saturday does not alleviate worry about Mr. Khashoggi’s fate. Nor does the record of recklessness built up by the Saudi regime under the crown prince, including waves of arrests of critics and dissenters, among them female activists who pushed for the right to drive; the extraordinary quasi-abduction of Lebanon’s prime minister; and the intemperate response to Canada’s justified criticism of Saudi Arabia’s human rights record.

Having disseminated the awful charge that Mr. Khashoggi was murdered, Turkey must immediately make public any evidence it has to back it up. Turkey must also spare no avenue to investigate.

The United States, too, should demand answers, loud and clear. President Trump has treated the Saudi crown prince as a favored ally, and his administration sidestepped criticism of the regime’s abuses. The State Department’s recent decision to certify that Saudi forces were taking adequate steps to avoid civilian casualties in Yemen — against all the evidence — sent a terribly wrong message. The United States must now make a concerted effort to determine all the facts about Mr. Khashoggi’s disappearance. If the crown prince does not respond with full cooperation, Congress must, as a first step, suspend all military cooperation with the kingdom.

We are hoping against hope that Mr. Khashoggi is unharmed and will soon return to his writing desk. If the reports of his murder prove true, grief must be accompanied by accountability for those who carried out the murder and those who ordered it.

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