A man cycles past signs bearing the name of U.S. President-elect Donald Trump in Tel Aviv on Nov. 14. (Baz Ratner/Reuters)

Gershom Gorenberg, an Israeli historian and journalist, is the author of “The Accidental Empire: Israel and the Birth of the Settlements, 1967-1977” and, most recently, “The Unmaking of Israel.”

The day Donald Trump named Stephen K. Bannon to the post of chief strategist in his new administration, Israel’s main public radio station devoted much of its international news hour to Bannon’s character. Distilled to essence, the message to listeners was: Be very anxious.

The station’s Washington correspondent, Nathan Guttman, spoke of “Bannon’s anti-Semitism,” stating it as fact rather than attributing it to someone else’s opinion. He reported that Bannon himself had bragged that his Breitbart News site was the platform for the “alt-right,” which Guttman explained in Hebrew as “nationalist racists.” And now, he concluded, Bannon “will be sitting in the White House next to the president.”

In Israeli government circles, on the other hand, the reaction to Trump and Co. has been welcoming. Israel’s ambassador to Washington, Ron Dermer, rushed to be the first foreign diplomat to meet the president-elect. Education Minister Naftali Bennett, head of the hard-right Jewish Home party, declared the morning after the election that Trump’s victory meant that “the era of the Palestinian state” as a possible political outcome “is over.” The leader of the even more extreme wing of that party, Agriculture Minister Uri Ariel, publicly thanked Bannon for his “friendship with Israel” and “opposition to the Iran nuclear agreement.”

I’ll put aside the stark strategic errors in this position — the dangers posed to Israel by permanent rule over the West Bank; by Iran renewing its nuclear arms program; and by Trump’s pro-Bashar al-Assad stance in Syria. Those issues all get wider attention. Let me focus on the blindness of celebrating the rise of authoritarian, bigoted leadership in the United States.

To start, Trump’s election is a crisis for American Jews. For a couple of generations, Jews in the United States have justifiably felt that America is qualitatively different from previous Diaspora homes — that they are not just tolerated but welcome. A large part of American Jewry is now in shock. Jews are concerned, or downright scared, about the mainstreaming of anti-Semitism in America.

Israel has always counted on Jewish solidarity as the basis for support from Diaspora Jews. Israel asks American Jews for political backing and financial support, constantly and especially when it believes it is threatened. Even the tensions among American Jews over Israel’s policies are predicated on the belief that what happens in Israel matters to Jews in the United States.

This has to go both ways. The largest Jewish community in the world outside Israel is in America. Israel and America are the two pillars of 21st-century Jewish life. For Prime Minister Benjamin Netanyahu and his government to ignore the anti-Jewish motifs of Trump’s campaign and the dangers of its aftermath, or to ignore or, worse yet, welcome Bannon  to the White House would flagrantly violate the principle of solidarity — and, in practical terms, risk alienating the liberal majority of American Jewry.

As seen in Bennett’s comments, those Israeli politicians who welcome Trump’s ascendance expect that an authoritarian U.S. administration won’t nudge Israel about human rights violations or about the anti-democratic character of the occupation. In the short term, they’re probably right. A president who wants to keep criticism of the regime out of theaters won’t bother Israel about maintaining democratic norms.

But they ignore the historical foundation of America serving as Israel’s superpower patron, as it has since the 1967 Six-Day War. A secret memo written after that war by President Lyndon B. Johnson’s adviser, McGeorge Bundy, pointed to political basis for U.S. support: the crisis forced “millions of Americans, in and out of government” to recognize that they couldn’t live with Israel’s defeat, which would have meant its destruction.

This recognition, I’d argue, rested on two links between the American public and Israel. The first was identification with Israel as a democracy. This connection has been strained by the Israeli government’s disinterest in ending the occupation. It survives because, even now, Israel is the only lasting, functioning democracy in the Middle East, at least within its pre-1967 borders.

But a U.S. administration that resonates with authoritarianism has much more powerful and strategically useful partners available — as Trump’s admiration for Vladimir Putin’s Russia shows. Israel can easily become an inconvenience.

The other emotional basis for the alliance has been America’s post-Holocaust empathy for Jews and respect for their painful past. Israel was created in large part in response to racist nationalism of the anti-Semitic variety. But that connection, too, is endangered when the president, the person most covered by the American media, propagates anti-Semitic conspiracy theories and draws fervent support from white supremacists.

Given Israel’s dependence on the United States, I’d understand diplomatic caution — even though this was never part of Netanyahu’s relationship with the Barack Obama. But at an absolute minimum, Netanyahu should be publicly voicing concern about anti-Semitic incidents in the United States before and after the election. Some leaked comments about Trump’s dangerous appointments are appropriate. Behind the scenes, a full-scale strategic assessment of the relation with the new administration is needed. Israel should, indeed, be anxious.