When Benjamin Netanyahu meets with Barack Obama on Monday, the main issue will be trust. Obama will ask that Israel trust America’s determination to stop Iran, and trust that when he says all options are on the table he means it. Netanyahu will likely be thinking about May 1967.

In late May 1967, Israeli Prime Minister Levi Eshkol dispatched his foreign minister, Abba Eban, to Washington. Egyptian and Syrian troops were pressing on Israel’s borders; Egypt had imposed a naval blockade on the Straits of Tiran, Israel’s shipping route to the east. Eban’s request of President Lyndon Johnson was that America honor its commitment to back military action if Egypt blocked the Straits of Tiran. That commitment had been made by Secretary of State John Foster Dulles in 1957, to secure Israeli withdrawal from the Sinai desert following the 1956 Suez War. Only a declaration by Johnson that he intended to immediately open the straits to Israeli shipping even at the risk of war--one idea was for the U.S. to lead an international flotilla--could stop a unilateral Israeli strike. Though Johnson was viscerally pro-Israel, he proved unable or unwilling to honor Dulles’ commitment. Preoccupied with Vietnam, Johnson wasn’t ready to support another war, let alone initiate one.

Even if Barack Obama is truly the pro-Israel president his Jewish supporters claim he is, the Johnson precedent tells us that it may not matter. Like Johnson, Obama presides over a nation wary of another military adventure, especially in the Middle East.…

What the world remembers of the Six Day War era is Israel’s military victory in June 1967. But these days Israelis are recalling the vulnerability of May 1967, in the weeks that preceded the victory. To be sure, Israelis understand that, in several crucial ways, today is different.… Then, Israel was entirely on its own in facing the threat on its borders. Today, by contrast, many countries, including in the Arab world, regard a nuclear Iran as a very real threat. In 1967, the war was localized, while this time the consequences of an Israeli preemptive strike will directly affect the international community and especially the United States--and perhaps not only economically.… And that could risk the stability of the American-Israeli relationship.

The Iranian nuclear threat could force Israel to choose between two of its essential national values. On the one hand, there is the commitment to Jewish self defense. On the other hand, there is the longing to be a respectable member of the international community. Allowing an enemy that constantly threatens Israel’s destruction to acquire the means to do so would negate Zionism’s promise to protect the Jewish people. And launching a preemptive strike without American backing could lead to Israel’s isolation.…

In this excruciating dilemma, the question of whether Israel can trust the administration to act militarily against Iran becomes all the more crucial. Israeli leaders believe that their window of opportunity in launching a preemptive strike will be closing in the coming months. America, though, with its vastly superior firepower, could retain a military option even after Israel’s lapses. In other words: An Israeli decision not to strike this year will mean that it effectively ceded its self-defense--against a potentially existential threat--to America. When Obama tells Israel to give sanctions time, what he is really saying is: Trust me to stop Iran militarily when you no longer can.

Yet the message from Washington in the last few weeks has only reinforced Israeli suspicions that we are back in May 1967. The spate of administration leaks to the media questioning Israel’s military capability in confronting Iran has undermined Israeli confidence in American resolve. An administration serious about stopping Iran to the point of military intervention would convey messages that raise Iran’s anxiety, not Israel’s. By insisting that Israel’s military threat isn’t credible--without at the same time explicitly stating that America’s military threat is--the administration reassures Iran that it has little to fear from military action. The Israelis can’t and the Americans won’t.…

Faced with an imminent existential dilemma, Israel will probably opt for preemptive self-defense, even if that means risking its special relationship with America.… The precedent of the two Israeli attacks against Arab nuclear facilities--in Iraq in 1981 and in Syria in 2007--reinforces Israeli determination to stop Iran, unilaterally if necessary.…

In better times, the two allies might have been able to navigate these conflicting needs. But in the absence of mutual trust, what could remain are conflicting perceptions of interest.