(Bloomberg Opinion) -- In the first days of 2021, while the world has been riveted by the dramatic rise of Covid-19 and the spectacular collapse of Donald Trump, Israel has been forced to pay attention to a third menace: Iran's fast escalation toward a nuclear weapon.On Jan. 2, Amir Ali Hajizadeh, a senior commander of the Iranian Revolutionary Guard, issued a warning to Israel on state-run Al-Manar television channel. “We have a general order from the Guide, Ali Khamenei to level Haifa and Tel Aviv to the ground in case any foolishness is committed against Iran, and we have worked over the past years to be able to do so.”Two days later, Iran formally announced that it has begun enriching its stockpile of uranium to 20% purity, in violation of its commitment under the Iran nuclear agreement, the JCPOA. Unhindered, Tehran could attain one or more nuclear weapons, possibly within a few months.Israeli Prime Minister Benjamin Netanyahu responded immediately by declaring he will not allow Iran to manufacture nuclear weapons. This has been Israel’s strategic doctrine, applied not only to Iran but all its declared enemies, since Prime Minister Menachem Begin ordered the destruction of Iraq’s reactor in 1981.Present military reality is not so simple. Tehran has the ability to hit Israeli targets with missiles launched from within Iran itself, or with conventional missiles launched by its proxies in Lebanon and Gaza, and perhaps from Iraq as well. But Tehran is far from capable of “levelling major cities,” and Israel’s response to such an attack would be prohibitively devastating. On the other hand, there are limits to what Israel can do militarily. Iran has learned the lesson of previous Israeli strikes on neighboring nuclear facilities. It no longer presents one single nuclear reactor as a target. Its enrichment facilities are spread throughout the country. Israel, in the opinion of leading strategists here, lacks the ability to take out these sites with a few clean strokes.The only country capable of such an operation is the United States. The problem of Iran’s new nuclear escalation will now wind up at the Biden White House.Tehran’s condition for reversing the escalation is a U.S. agreement to return to the JCPOA status quo ante. This is unacceptable to Israel and its Sunni Arab allies. The deal doesn’t limit Iran’s ballistic missile program, which is an integral part of a broader nuclear weapons arsenal. It ignores the fact that Iran has turned Lebanon and Gaza into launching pads. And it elides the obvious: Eliminating the Jewish State is a core goal of the Islamic Republic. From the Israeli point of view, all Iranian nuclear activity will ultimately lead to the fulfillment of that goal.This week, Netanyahu seized on this point. “Iran’s decision cannot be explained in any way except as a continued realization of its intention to develop a military nuclear program.”The remark was addressed to the Israeli public which will be going to the polls in less than three months. Bibi’s political opponents, whatever their virtues, lack both the national security credentials and foreign policy experience to confront the new strategic threat that has emerged. Standing up to Iran is a major part of Netanyahu’s electoral appeal.During the Trump administration, that was easy. If Trump had been re-elected, Bibi (and the Sunnis) might well be pushing for the American-led nuclear disarmament of Iran, or for a change in regime in Tehran, though for all his rhetoric Trump pulled back from broader entanglements during his term. That’s now off the table, unless Iran miscalculates by taking further steps toward a bomb in 2021.In talks with the Biden administration, Israel will argue that accepting an Iranian ultimatum on the JCPOA would be seen by U.S. allies in the Middle East as a dangerous capitulation. It will call on the U.S. to retain harsh economic sanctions against the most bellicose elements of the Iranian regime and remain outside the framework of the nuclear deal as it presently stands.These are Trump policies. That may now be sufficient to make them toxic to many in Biden’s camp. But though his legacy now lays in tatters, not everything Trump did is the Middle East is wrong. His hardline has renewed American credibility in the region, led to stronger alliances and given Washington greater diplomatic influence in the region.Biden clearly wants to return to the JCOPA. His chief advisors are now speaking publicly about additional conditions and improvements to the plan. Netanyahu can live with that, on condition that Israel (and his Sunni partners) are not excluded, as they were last time, from participating in the negotiation. Engaging with Iran could be a springboard for something even more ambitious than an arms control agreement.Including Israel and Saudi Arabia (also a target of Iran’s weapons program) in the talks is not only reasonable, it could foster confidence in Jerusalem and Sunni capitals that any new deal takes their concerns and interests into account. If Iran's intentions are benevolent, agreeing to let Israel and Saudi Arabia participate, even indirectly (as, for example, Israel negotiates with Gaza via Egypt), could be a step toward an eventual diminution of the conflict. In the meantime, the U.S. should make it clear to Iran (and to the other signatories) that it will not return to any form of the JCPOA until unilateral escalation toward a bomb is reversed. Israel should put aside threats to act on its own as if it was still 1981. The strategic threat posed by a nuclear Iran is genuine. There may come a time when Israel decides it has no choice but to invoke the Begin Doctrine. But this isn’t it.This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.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.For more articles like this, please visit us at bloomberg.com/opinionSubscribe now to stay ahead with the most trusted business news source.©2021 Bloomberg L.P.