During a crackdown on political dissent last year, the Saudi Arabian government arrested dozens of peaceful individuals. Those seized in just a single week’s raids, The New York Times reported, included “clerics, academics, a poet, an economist, a journalist, the head of a youth organization, at least two women, and … a son of a former king.” None of the detainees was known to advocate extremist or criminal acts; their offense was that they failed to publicly applaud Riyadh’s diplomatic and economic campaign against neighboring Qatar.

That wave of arrests 13 months ago prompted Jamal Khashoggi, a former Saudi editor living in quiet self-exile, to break his silence. He wrote a column for The Washington Post decrying the “climate of fear and intimidation” in his homeland. He struggled to understand how Crown Prince Mohammed bin Salman, widely hailed as a reformer, could preside over such repression.

“I am raising my voice,” he wrote, because “to do otherwise would betray those who languish in prison. I can speak when so many cannot.”

In subsequent columns, Khashoggi kept raising his voice about the Saudi government’s human rights abuses and strangling of dissent. A few other journalists and activists kept raising their voices too. But only a few. Much more prevalent were the upbeat accounts of how the crown prince was such an impressive force for reform, moderation, and women’s emancipation. The prevailing attitude was captured in the headline of one effusive column by Thomas Friedman: “Saudi Arabia’s Arab Spring, At Last.”

As the whole world knows, Khashoggi has now been silenced. If reports are accurate, he was tortured, murdered, and dismembered at the Saudi consulate in Istanbul earlier this month; the gruesome crime, it appears, was committed by a Saudi death squad that included several men with direct ties to the crown prince.

And so once again the West is being taught a lesson it never seems to master for long: Enlightened despots aren’t enlightened. Any regime that imprisons, tortures, or kills people because of their opinions is by definition an enemy of the free world — our enemy. Tyrants may embrace capitalism or talk up political reforms. They may legitimately win an election or crack down on corruption. They may quote Thomas Jefferson or sign arms-reductions treaties. They may even make the trains run on time.

But if they jail or murder dissidents, they are not our friends. Granted, our governments may have interests in common, our businesses may buy and sell from each other, and our intelligence services may collaborate against a mutual foe. But at the most fundamental level, there is an unbridgeable moral gulf between a liberal democracy like the United States and a brutal dictatorship like Saudi Arabia. We forget that at our peril.

So-called foreign policy “realists” don’t go in much for moral gulfs. They tend to regard human rights as a minor concern in international relations. President Trump’s unwillingness to let Khashoggi’s fate undermine US-Saudi relations is rightly drawing disgusted criticism. But how different is it from George H.W. Bush’s insistence in 1989 that the Tiananmen Square slaughter not interfere with US-China relations? Or from Barack Obama’s refusal to condition normalized relations with Cuba on a softening of the Castro regime’s ruthless persecution of dissidents?

To be sure, Planet Earth is a messy place, and statecraft cannot be reduced to mere slogans. Nonetheless, no objectives matter more in the long run than the survival of liberty and human rights. That should always be a pillar of American foreign policy, as it was with the Truman Doctrine in the 1940s, the defense of South Korea in the 1950s, and support for Poland’s Solidarity movement in the 1980s.

Yet when it comes to Saudi Arabia, liberty and human rights have always been treated as a non-issue. Though the House of Saud has always been cruel, intolerant, and cutthroat, the United States has for decades showered the Saudi regime with diplomatic and military support on the grounds that it provides stability (not to mention a steady flow of oil) in a volatile part of the world. The fulsome praise for Crown Prince Mohammed has been merely the latest iteration of the myth of what George W. Bush once called the “eternal friendship” between America and Saudi Arabia.

There is no such friendship. With the Saudis there is only realpolitik, and to confuse the two is dangerous. The kingdom is ruled by a pitiless crime family, one that flogs and beheads dissidents for speaking their minds, that prohibits the practice of any religion but Islam, and that disseminates fanatical Wahhabi Islamism across the globe. The Saudis execute prisoners at the rate of one every two days, often for crimes, such as apostasy and witchcraft, that don’t exist in the civilized world. “Saudi-funded radicals have been involved in every civil war across the Muslim world over the last decade,” writes Michael Brendan Dougherty in National Review. There are not many societies with which we have less in common.

No one should have been surprised in 2001 that Osama bin Laden and 15 of the 9/11 terrorists were Saudi. No one should be surprised in 2018 if it is proven that Riyadh dispatched a team of killers to literally butcher a nonviolent dissident in a foreign consulate. Saudi Arabia is an evil desert empire, and such things are to be expected.

Time and again, credulous Western elites convince themselves that one of the world’s dictators has become a champion of reform. Time and again, they learn how wrong they were. Jamal Khashoggi will be remembered. The lesson of his death probably won’t.

(Jeff Jacoby is a columnist for The Boston Globe).