On Thanksgiving Day, Donald Trump held a video press conference from his resort in Florida. Unsurprisingly, he was asked why he continues to stand up for Saudi Arabia’s Crown Prince Mohammed bin Salman, even though the Central Intelligence Agency believes he personally ordered the murder of Washington Post columnist Jamal Khashoggi.

Trump responded with his usual America First talking points: Saudi Arabia spends billions of dollars on American military equipment and technological products, creating “hundreds of thousands of jobs” for Americans; the Saudis have, at the President’s request, held down the price of oil, thus averting economic disaster and keeping cars on the road across the United States. Trump also invoked Saudi Arabia as a necessary American ally and a partner in the effort to contain Iranian aggression.

Then he added a new, unexpected rationale for his defence of the Crown Prince, who is widely known as MBS: “If you look at Israel, Israel would be in big trouble without Saudi Arabia.”

The claim was met with scepticism in Jerusalem. Israel does not regard Saudi Arabia as an essential partner in its national security. The kingdom has no significant role to play in Israel’s confrontation with its most immediate threats: Hamas in Gaza, and Hezbollah in Lebanon. And Israeli military planning doesn’t envisage, much less require, Saudi assistance in the event of a flare-up with Iran.

Yes, the two countries share the goal of defeating, or at least containing, Iranian expansion. But their relationship, which is still officially on the down-low, depends on interests, not personalities. It predates MBS, and it will last as long as the two countries have common goals.

This is not to say that Israel doesn’t appreciate its informal relationship with Saudi Arabia, or MBS’s role in fostering it. Doors are being opened to Israel across the Arabian Peninsula. This month, Prime Minister Benjamin Netanyahu broke new ground by travelling to Oman, and two Israeli government ministers visited Abu Dhabi and Dubai. Bahrain may be next on Netanyahu’s travel plan. These visits would not be possible without the blessing of Saudi Arabia — specifically of King Salman bin Abdulaziz and his favourite son.

Netanyahu regards stability in the Saudi leadership as good for his country. That is why, after declaring the murder of Jamal Kashoggi as “horrendous”, he advised Trump to stand by the Crown Prince. He argued that the US cannot engineer a change in the palace in Riyadh. Eisenhower did that in Iran, in 1953, and the US is still suffering the aftershocks.

The Saudi royal court is not transparent, but there is little sign that the Crown Prince is at risk of being dethroned. Former MBS rival Turki al-Faisal, ex-head of Saudi intelligence, told AP that King Salman and MBS enjoy “extraordinary support” at home. A more reliable indicator is MBS’s trip this week to the United Arab Emirates, Bahrain, Egypt and Tunisia. Endangered autocrats do not customarily leave home.

MBS has arrived in Buenos Aires where he will attend the G20 summit. Turkish president Recep Tayyip Erdogan, his chief tormentor in the Khashoggi murder, will be there, too, and can be counted on to raise the matter again. Human Rights Watch has asked Argentine public prosecutors to investigate the prince’s role in war crimes in Yemen, as well as in the Khashoggi murder.

Although Trump has no formal meeting planned with MBS, he may again be forced to defend the prince. He will deploy his America First arguments, but they will not convince the President’s many detractors. They don’t even work on Republican leaders such as Lindsay Graham, who want MBS called to moral account by Congress.

“Israel” is a magic name with the Evangelical Republican base. That may well be why Trump tossed it into his rationale salad on Thanksgiving. This may also explain why this week, he cited Israel’s security as a reason for keeping US troops in the Middle East. He need fear no immediate pushback from Israel. Netanyahu has no reason to embarrass Trump, enrage MBS or get further drawn into the drama of the Kashoggi murder. But Israel’s leader knows full well that his country will not be “in big trouble” if Trump doesn’t stand by MBS.

• Zev Chafets is a journalist and author of 14 books. He was a senior aide to Israeli Prime Minister Menachem Begin and the founding managing editor of the Jerusalem Report Magazine