Have President Trump and his son-in-law bet their entire Mideast policy on a reckless 32-year-old Saudi crown prince who is getting in over his head?

That’s the question that should grab Americans as we watch the wild game of thrones playing out in Saudi Arabia, where, last week, Saudi Crown Prince Mohammed bin Salman (known as MBS) arrested 11 princes along with an additional 190 officials and businessmen. Another prominent prince died in a mysterious helicopter crash.

What’s riveting is the degree to which Trump has fully embraced the youthful prince (and his elderly father, King Salman). Moreover, first son-in-law Jared Kushner, a new buddy of the young prince, has made three trips to Riyadh this year, the latest a secret four-day visit last month.

Trump tweeted, in the midst of his Asia trip: “I have great confidence in King Salman and the Crown Prince of Saudi Arabia. They know exactly what they are doing.” Clearly the purge doesn’t bother a president who admires strongmen.

More to the point, Trump and Kushner appear to be relying on the crown prince to spearhead a Sunni Arab campaign that will roll back Shiite Iran’s expanding influence in the Mideast. A look at the prince’s track record should have dampened their enthusiasm for MBS.

Sure, Prince Mohammed talks a good game. He says he wants to modernize the kingdom, fight corruption, let women drive, and promote a more moderate form of Islam. That would certainly be a welcome change, since Saudi Arabia’s export of their fundamentalist Wahabi variant of Islam has paved the way for the rise of jihadism around the world.

Yet his roundup of the kingdom’s most prominent businessmen looks more like a Putinesque shakedown than a move toward a transparent system. Any seized funds may be used to underwrite MBS’s grandiose scheme to build a new $500 billion high-tech metropolis in the desert called NEOM.

As for moderating the Saudi brand of Islam, that would be a boon to the kingdom and the world. But although some clerics have been arrested, and religious police lectured, the Crown Prince has cracked down as hard or harder on intellectuals and peaceful activists.

So it appears that Prince Mohammed’s main goal is to solidify power in his hands alone, in a country where kings have long ruled by consensus. Whether he has the judgment to handle that power is questionable.

MBS’s impulses are most questionable when it comes to his campaign against Tehran, waged all over the region. The Saudi track record versus Iran is one of unmitigated failure — despite U.S. backing.

Yet this is the campaign Trump and Kushner are counting on the prince to win.

In Syria, President Barack Obama subcontracted to the Saudis to arm and fund Sunni rebels against President Bashar al-Assad. The winner: Assad — backed by Russia airpower and Shiite militiamen directed by Iran.

In Iraq, after the fall of Saddam Hussein the Saudis refused U.S. requests to help Iraqi governments counterbalance Iranian influence.

In neighboring Yemen, just after his father became king, MBS launched a war against Houthi insurgents who had ties to Tehran. The war has dragged on for two years, as Saudi and United Arab Emirates fighter jets bomb civilians relentlessly, with full Trump support and advanced U.S. weapons. Despite thousands of civilian casualties and a humanitarian disaster, it’s clear the Saudis can’t win without an unlikely ground invasion.

In Qatar, the Crown Prince launched a blockade of the small, oil-rich Gulf state, supposedly due to Iranian influence. Trump tweeted his strong approval (and is now belatedly trying to undo the damage). The result: Qatar has been pushed closer to Tehran, and the unity of Sunni Gulf Arabs against Tehran has been split.

And, in his latest move versus Iran, MBS just forced the resignation of Lebanon’s Sunni prime minister, Saad Hariri. Lebanon now fears a new sectarian civil war.

With the prince’s terrible track record so far, you’d think that Trump would be branding MBS a loser. Or at least proceeding with great caution.

Instead, Trump and Kushner have heedlessly harnessed their Mideast hopes to an undependable Saudi prince.

Trudy Rubin is an editorial-board member for the Philadelphia Inquirer.