By the summer of 2013, President Obama had convinced several key Israelis that he wasn’t bluffing about using force against the Iranian nuclear program. Then he failed to enforce his red line against Syrian dictator Bashar Assad—and the Israelis realized they’d been snookered. Michael Oren, the former Israeli ambassador to the United States, recalls the shock inside his government. "Everyone went quiet," he said in a recent interview. "An eerie quiet. Everyone understood that that was not an option, that we’re on our own."

Reading Oren’s new memoir Ally, it’s clear that Israel has been on her own since the day Obama took office. Oren provides an inside account of relations between the administration of Barack Obama and the government of Bibi Netanyahu, and his thesis is overwhelming, authoritative, and damning: For the last six and a half years the president of the United States has treated the home of the Jewish people more like a rogue nation standing in the way of peace than a longtime democratic ally. Now the alliance is "in tatters."

Oren is not a conservative looking to make a political issue of support for Israel. Indeed, by Washington Free Beacon standards, he’s something of a squish. The author of a classic history of U.S. involvement in the Middle East and a sometime professor at Yale, Harvard, and Georgetown, Oren served for five years as a contributor to the New Republic, has contributed to the New York Review of Books, and supports what he calls a "two-state situation" focused on institution-building and economic aid to the West Bank. He’s a member of the Knesset, but not of Netanyahu’s Likud Party. He joined the comparatively dovish Kulanu Party last December.

Oren’s credentials and relationships make him hard to dismiss. "The Obama administration was problematic because of its worldview: Unprecedented support for the Palestinians," he told Israeli journalist David Horovitz, another centrist, this week. Obama and his lieutenants, including Hillary Clinton, have often behaved as if the Palestinians don’t exist—Palestinian actions, corruption, incitement, campaigns of de-legitimization and terrorism are overlooked, excused, accommodated. Oren tells the story of what happened when Vice President Joe Biden asked Palestinian president Mahmoud Abbas to "look him in the eye and promise that he could make peace with Israel." Abbas looked away. The White House did nothing.

It was Israel that had to agree to a settlement freeze before the latest doomed attempt at peace negotiations; Israel that had to apologize for possible "mistakes" against the Gaza flotilla; Israel that had to close Ben Gurion airport; Israel that faced a "reevaluation" of her diplomatic status after Bibi’s reelection. Obama addresses the bulk of his lectures on good governance and democracy and humanitarianism not to the gang that runs that West Bank, nor to the terrorists who rule Gaza, but to Israel. During last year’s Gaza war, the State Department was "appalled" by civilian casualties inflated and trumpeted by Hamas propagandists. Oren points out that in the past the president had used the word "appalling" to describe the atrocities of Muammar Qaddafi. Qaddafi and the IDF—two peas in a pod, according to this White House.

What Obama wanted was to create diplomatic space between America and Israel while maintaining our military alliance. Oren says military-to-military relations are strong, but the diplomatic fissure has degraded Israel’s security. America, he says, provided a "Diplomatic Iron Dome" that shielded Israel from anti-Semites in Europe, at the U.N., and abroad whose goal is to delegitimize the Jewish State and undermine her economically.

This rhetorical missile shield is slowly being retracted. The administration threatens not to veto anti-Israel U.N. initiatives, Europe is aligning with the Boycott Divestment Sanctions (BDS) movement, and anti-Israel activism festers on U.S. campuses. Obama’s unending criticism of Israel, and background quotes calling Israel’s prime minister a "chicken-shit" and a "coward," provide an opening for radicals to go even further.

The diplomatic rupture endangers Israel in another way. It preceded Obama’s quest for détente with Iran, Israel’s greatest enemy and most pressing threat. Oren was outraged in 2013 when he learned that the administration had been conducting secret negotiations with the mullahs. Now, with the United States about to clear the way for Iranian nukes and flood the Iranian economy with cash, Israel is all the more at risk.

"Obama says Iran is not North Korea," Oren said, "and Bibi says Iran’s worse than 50 North Koreas. It all comes down to that." Fixated on striking a deal, Obama is preparing to concede the longstanding demand that Iran disclose its past nuclear weapons research, is ignoring the issue of Iranian missile development, and is standing idle as Iran props up Assad, arms Hezbollah with rockets, and promotes sectarianism in Iraq. Israel is hemmed in—by Iranian proxies and Sunni militants on its borders, by the threat of a third intifada on the West Bank, by global nongovernmental organizations, by a condescending, flippant, and bullying U.S. president whose default emotional state is pique.

As if to make Oren’s case for him, the Obama administration responded to the publication of Ally with neither silence nor a reiteration of American policy toward Israel but with vituperation, demanding that both Kulanu Party chairman Moshe Kahlon and Prime Minister Netanyahu apologize for criticisms Oren had made. Kahlon sheepishly distanced himself from Oren, and Netanyahu won’t comment publicly, but the episode illustrates precisely the model of U.S.-Israeli relations outlined in this book: A "family" argument where the criticism runs in only one direction. On the one hand, when the supreme leader of Iran calls John Kerry a liar and details plans to destroy Israel, the Obama administration brushes it off. On the other, when a former ambassador writes a memoir based on a diary he kept while in office, the administration loses its mind.

The alliance has faltered to such a degree that Oren is morose. He wonders whether Israel is in the same precarious position it was in 1967, before the Six Day War, or in 1948, when it came close to never being born. Neither option is comforting. David Horovitz asked him, "Are people going to look back in a few years’ time and say, ‘This is what they were talking about in Israel as Iran closed in on the bomb and they were wiped out?’" Oren’s response: "It’s happened before in history, hasn’t it?"

It has. And it may happen again. But whatever happens, thanks to Michael Oren, history will know that an inexperienced and ideologically motivated president drove a lethal wedge between the United States of America and the young, tiny, besieged Jewish State.