For years, Israel and the American Jewish community have been sounding the alarm over Iran's nuclear program. This alarm is wholly justified, given the Iranian regime's record in the nuclear arena, the views and behavior of many of its officials over the years, and its support of international terrorism.

It is this alarm, today shared by nations around the world, which led international leaders to come together last month with their Iranian counterparts in Geneva. There, they hammered out an interim agreement that opens the door for a possible final accord that verifiably limits Iran's nuclear program and nuclear ambitions.

Skepticism about Iranian intentions in negotiations is natural, as are fears that Iran may exploit diplomacy for its own purposes. However, this interim agreement is indisputably good news -- both for Israel and the United States -- and should be welcomed by American Jews.

During the deal's six-month interim period, the agreement freezes progress on key elements of Iran's nuclear program and requires Iran to effectively give up its stockpile of highly enriched uranium -- material that can be used for nuclear weapons. For these reasons alone, the agreement represents a major achievement that sets back the immediate threat of a nuclear-armed Iran. In the longer term, the agreement opens the door for a potential final accord that can prevent a nuclear-armed Iran, holding out the promise of a more secure Israel, a more stable Middle East, and a safer world. Anyone who cares about Israel, U.S. national security, or stability in the Middle East should embrace this historic diplomatic breakthrough.

The interim agreement also provides Iran a measure of relief -- an achievement that Iranian negotiators need as they defend and sell diplomacy to their own constituents. This relief, however, is mainly in the form of releasing some frozen Iranian assets, and can be shut off if negotiations fail. In the meantime, far-reaching U.S. and international sanctions remain in place, and will stay there unless and until a final agreement is achieved and implemented.

Current Iran diplomacy is a test -- not only of Iran's readiness to demonstrably curb its nuclear ambitions, but also of the readiness of the U.S. and the international community to accept a diplomatic solution. If the effort fails due to Iranian disinclination to reach a final deal, the existing multilateral effort to pressure Iran will continue and likely deepen, with even greater sanctions and more serious threats of war. If it fails due to other parties' unwillingness to take "yes" for an answer from Iran, the result will only be worse options, and worse outcomes, for both the United States and Israel.

Take the issue of new sanctions. Some in the American Jewish community are pressing Congress to pass legislation imposing new sanctions immediately, or putting new sanctions on a hair-trigger. This approach signals a lack of seriousness about giving diplomacy a chance to work. If successful, it would discredit diplomacy, isolate the United States (and Israel) on the Iran issue, and likely lead to the dissolution of the international consensus that is the core of the existing Iran sanctions regime.

This approach could also lead many Iranians, both inside and outside government, to understandably conclude that the real agenda of the United States is not policy change in Iran, but regime change. Such a conclusion could in turn lead Iranian authorities to decide that crossing the red line and obtaining a nuclear weapon -- a decision that U.S. intelligence officials believe has not been made thus far -- is an existential necessity. At that point, the only options for the United States and Israel will be accepting a nuclear-armed Iran or war. Those who favor war should bear in mind that virtually all experts believe military engagement with Iran will, at best, delay Iran's nuclear program while hardening Iran's resolve to acquire a nuclear weapon to deter future attacks. And such a war, like any war, will be replete with unanticipated costs and consequences, and would deeply divide a war-weary American public.

Decades of experience have demonstrated that sanctions and threats, alone, will never resolve the challenge posed by Iran's nuclear program. War as an option of last resort is risky and problematic. What has always been needed is a combination of multilateral pressure and sustained, tough, multilateral diplomacy. Such diplomacy holds the promise of delivering a deal.

That is exactly what we have today. With it, for the first time since the Iranian revolution, there is the possibility of an agreement with Iran that can ratchet down the danger and the threat of a nuclear-armed Iran. American Jews who care about Israel should welcome the interim agreement that has already been achieved, and should support ongoing diplomacy to achieve a final accord that, to the greatest extent humanly and technically possible, forecloses the possibility of a nuclear-armed Iran.

This article appeared first on December 27, 2013 at The Jewish Chronicle.