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. ||||| Peter Bergen is CNN's national security analyst, a vice president at New America and a professor of practice at Arizona State University. He is the author of "The Osama bin Laden I Know: An Oral History of al-Qaeda's Leader." See more opinion at CNN. 
 
 (CNN) Jamal Khashoggi, a prominent Saudi writer, vanished on Tuesday after entering the Saudi consulate in Istanbul to obtain paperwork so he could marry his Turkish fiancée. He has not been seen or heard from since. 
 
 As a columnist for the Washington Post, Khashoggi was a frequent critic of the Saudi regime. Khashoggi was living in self-imposed exile in the United States. 
 
 On Saturday, Turkish officials told the Washington Post that Khashoggi was murdered at the Saudi consulate. 
 
 CNN has not been able to independently confirm these reports and a Saudi official has denied them. 
 
 Earlier in the week, Saudi Crown Prince Mohammed bin Salman had told Bloomberg News that Khashoggi had left the consulate unmolested, but if that was the case, why hasn't he contacted anyone? 
 
 Media outlets around the world have reported on Khashoggi's mysterious disappearance. If Khashoggi had left the consulate unharmed, it's inconceivable he wouldn't have informed his fiancée, family, friends and colleagues at the Washington Post. 
 
 I have known Khashoggi for more than a decade and am appalled at the possibility that the Saudi government would engineer the disappearance of a writer who worked tirelessly to promote civilized, humane values. 
 
 Khashoggi and bin Laden's paths diverged 
 
 I first came to know Khashoggi when I was reporting on Osama bin Laden. As young men, Khashoggi and bin Laden knew each other well because Khashoggi was the first journalist from a major Arab news organization to profile bin Laden when he was fighting the Soviets in Afghanistan in the late 1980s. Both men were idealistic and religious and were opposed to the communist invasion of a Muslim country and the brutal tactics of the Soviet military. 
 
 On May 4, 1988, Khashoggi wrote a story for Arab News that quoted bin Laden as saying, "It was God alone who protected us from the Russians during their offensive last year. Reliance upon God is the main source of our strength." 
 
 Seven years later, when bin Laden was based in Sudan, Khashoggi visited him there. Bin Laden told his old friend that that he was thinking of returning to Saudi Arabia and renouncing his war against the Saudi regime. That, of course, didn't happen -- and in 1996 bin Laden moved to Afghanistan, where he launched his war against the United States. 
 
 While bin Laden became the world's most wanted terrorist, Khashoggi went on to have a distinguished career as a writer and editor and also an adviser to Prince Turki al-Faisal, who was the Saudi ambassador to both the United Kingdom and the United States. 
 
 The totalitarian regime in Saudi Arabia 
 
 The disappearance of Khashoggi is of a piece with much that the Saudi regime of Crown Prince Mohammed bin Salman is doing. 
 
 In 2015, bin Salman, who is often referred to as MBS, launched a war in Yemen in which at least 6,500 civilians have been killed , many of them from Saudi munitions, according to the United Nations in a report that was released in August. 
 
 The UN report noted that, "air strikes have hit residential areas, markets, funerals, weddings, detention facilities, civilian boats and even medical facilities." 
 
 The Saudis have also arrested a range of civil society activists and conservative clerics, including some who may face death sentences. 
 
 Saudi prosecutors are seeking the death penalty for a 29-year-old Shia female activist accused of organizing demonstrations for greater Shia rights who was arrested in December. 
 
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 Similarly, the Saudis are seeking the death penalty for a prominent, reformist cleric, Salman Al-Oudah, who has called for elections in the Saudi kingdom. 
 
 Saudi Arabia was once a consensus-based absolute monarchy, but under MBS's direction it is increasingly becoming a secularizing totalitarian dictatorship. 
 
 While there is much to praise in some of what MBS has done, such as removing the feared religious police from the streets and making real efforts to reform the heavily oil-dependent Saudi economy, there is also much that is inexcusable. 
 
 There is no hard evidence as yet that Khashoggi was murdered, but if such evidence were to emerge and the Saudis are found to be responsible, the United States should impose sanctions on the Saudis just as the Trump administration did in August against the Russians following their use of a nerve agent to attempt to kill a former Russian agent and his daughter in the United Kingdom. 
 
 Khashoggi, after all, was both a legal resident of the United States and was employed by a major American media institution.
– Is Jamal Khashoggi alive or dead? It's time the US got involved to determine the truth about the missing Saudi Arabian journalist, declares an editorial in the Washington Post. Khashoggi, who contributes to the Post, hasn't been seen since Tuesday, when he entered the Saudi consulate in Istanbul. Turkish officials claim the Saudis murdered him, but the Saudis deny it, and Turkey hasn't produced any proof. "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," says the editorial. Saudi Arabia must explain the suspicious arrival in the country of 15 security officials just before Khashoggi's disappearance, and Turkey must produce clear evidence to back up its claims. "The United States, too, should demand answers, loud and clear," says the editorial, noting that President Trump has been on good terms with the de facto Saudi leader, Crown Prince Mohammed bin Salman. "The United States must now make a concerted effort to determine all the facts about Mr. Khashoggi's disappearance," write the editors. And if the Saudis balk at cooperation, Congress should suspend all military cooperation with the nation. Peter Bergen of CNN writes that he has known Khashoggi for a decade. "If Khashoggi had left the consulate unharmed"—as the crown prince himself insists—"it's inconceivable he wouldn't have informed his fiancee, family, friends, and colleagues at the Washington Post," Bergen notes.