Amos Yadlin, a former chief of Israeli military intelligence, is director of Israel’s Institute for National Security Studies.

This fall, all the boxes will be checked for an Israeli attack on Iran’s nuclear facilities. Consider this Aug. 1 statement of Prime Minister Benjamin Netanyahu: “Time to resolve this issue peacefully is running out.” Defense Minister Ehud Barak said Thursday that “there are risks in the situation today . . . [but] it’s infinitely more dangerous . . . to deal with a nuclear Iran in the future.” When President Shimon Peres added his voice to the public opposition to a unilateral Israeli strike this fall, an associate of Netanyahu accused Peres of having “forgotten” the role of Israel’s president. Israeli logic holds that it must choose between, as the media reports put it, the bomb and the bombing.

The Iranian regime will soon possess enough low-enriched uranium to build an arsenal of nuclear bombs. Moreover, Iran’s deputy navy commander, Abbas Zamini, said in June that “preliminary steps in making an atomic submarine have started.” This provides Iran an excuse to continue enriching its uranium stockpiles to weapons-grade levels. Meanwhile, “P5+1” negotiations have ended without an agreement. Western-imposed sanctions have damaged Iran’s economy but have not produced a shift in the regime’s political thinking or nuclear drive. Covert operations against Iran’s nuclear facilities and scientists — for which no one has claimed responsibility — have similarly failed to stop the program. Despite some political difficulties, the regime in Tehran continues to reign.

Add to all this the issue of the “zone of immunity” — the point at which Iran’s nuclear facilities would become immune to an Israeli military strike. For Israel, the conclusion is clear.

As Netanyahu and Barak rule out arguments against an attack, they are watching developments in the Sunni world. Saudi Arabia, Iraq and Libya have increased oil production, reducing fears that an attack would send prices skyrocketing at a time of international economic angst. The bleeding Assad regime in Syria is in no position to support Tehran. Rising Sunni-Shiite tensions in the region could potentially ease collective Islamic outrage over an Israeli attack on Iran.

Netanyahu and Barak are acutely aware of the U.S. election calendar. Moreover, as Defense Secretary Leon Panetta said in an Aug. 1 news conference with Barak, Iran’s pursuit of nuclear weapons “poses a threat not only to Israel, but to the entire region. The United States is also a focus of that threat as indeed [is] the rest of the world.”

Despite seeing eye to eye on this strategic goal, the United States and Israel disagree on the timeline for possible military action against Iran. Superior U.S. operational capabilities mean that it will be another year or two before Iran’s nuclear sites become “immune” to a U.S.attack. Unlike Israel, therefore, the United States can afford to delay beyond this fall, which is precisely what the Obama administration wants. Leave your planes in their hangars, the president has signaled to Israel.

A long-standing principle of Israeli defense doctrine is that it will never ask the United States to fight for it. That is why Israel’s political leaders have emphasized that when it comes to national security, Israel will ultimately decide and act on its own. Unfortunately, what Israeli leaders may not fully grasp is that while they can attack alone, Israel will need the United States both the day after and the decade after a strike to ensure that Iran does not reconstitute its program. Disregarding U.S. requests to delay would not encourage such support.

Only by framing a nuclear-armed Iran as an impermissible threat to the national interests of the United States and its allies in the Persian Gulf can President Obama bridge this gap between Israeli creed and need. He must convince Israel, Iran, Russia and even Saudi Arabia that the U.S. military option is credible and effective.

A gesture directly from Obama could do it. The U.S. president should visit Israel and tell its leadership — and, more important, its people — that preventing a nuclear Iran is a U.S. interest, and if we have to resort to military action, we will. This message, delivered by the president of the United States to the Israeli Knesset, would be far more effective than U.S. officials’ attempts to convey the same sentiment behind closed doors. The administration should also take five immediate steps to convince allies and adversaries alike that military action is real, imminent and doable — which are key to making it less likely.

First, Obama should notify the U.S. Congress in writing that he reserves the right to use military force to prevent Iran’s acquisition of a military nuclear capability. This would show the president’s resolve, and congressional support for such a measure is likely to be strong. Forty-four senators signed a bipartisan letter to Obama in June, urging him to “reevaluate the utility of further talks at this time” and focus instead on sanctions and “making clear that a credible military option exists.”

Second, Washington should signal its intentions via a heightened U.S. military presence in the gulf, military exercises with Middle East allies and missile defense deployment in the region. Media coverage of these actions should be encouraged.

Third, Washington should provide advanced military technology and intelligence to strengthen Israel’s military capabilities and extend the window in which Israel can mortally wound Iran’s program. This support would be contingent on Israeli pledges to give sanctions and diplomacy more time to work.

Fourth, U.S. officials should speak publicly about the dangers of possible Iranian nuclear reconstitution in the wake of a military strike. Perhaps the most cogent argument against a unilateral Israeli strike is that it would quickly lead to the disintegration of Western sanctions. Without the inhibitions of a sanctions regime, Iran could quickly reconstitute its nuclear program — this time bunkered entirely underground to protect against aerial strikes. If Iran sees military action by Israel or the West as an absolute end to its nuclear ambitions, it will be more reluctant to risk things.

Fifth, Obama should publicly commit to the security of U.S. allies in the gulf. This would reassure jittery friends in the region and credibly anchor the U.S. last-resort military option to three powerful interests: U.S. national security, Israeli security and the security of allied states.

Israel cannot afford to outsource its security to another country. But if the United States wants Israel to give sanctions and diplomacy more time, Israelis must know that they will not be left high and dry if these options fail. Ironically, the best assurance the U.S. president can give Israel is a commitment to, if all else fails, resort to military action to protect critical U.S interests. But time is running out to make this commitment credible to the people of the United States, Israel and Iran. As the adage goes, if you want peace, prepare (credibly) for war.