From the brink of war, the Middle East has moved at dizzying speed to the cusp of peace. Or so we are led to believe.

The issues at hand are Iran and Syria.

In Syria, the regime of Bashar Assad claims to be submitting vital data on its chemical arsenal, under the watchful eye of the Russians, in advance of a November deadline to disarm itself of these monstrous weapons. If the Obama administration is looking to save face from its shabby climb-down in the face of Syrian brutality and Russian duplicity, it can always assert that the Syrian disarmament process is yielding positive effects in neighboring Iran. The White House can argue that the renewed impetus for a deal on Iran’s nuclear program is the result of a credible threat of force against Assad, Tehran’s key regional ally.

But I suspect that the White House is going to have trouble selling this line on Iran, especially when you take its to-ing and fro-ing over Syria into account.

For one thing, betting on the ability of Hassan Rouhani, Iran’s new president, to deliver a deal is a seriously risky business. Rouhani says Iran does not intend to build a nuclear weapon. Even if he is sincere, there is no solid evidence that he can carry the rest of the Iranian regime with him, particularly given that, as president, he is subordinate to both the Supreme Leader Ayatollah Ali Khamenei and the powerful Islamic Revolutionary Guard Corps (IRGC).

What strikes me, in fact, is that for all the gushing attention paid to Rouhani’s charm offensive, which has been astutely timed to coincide with his arrival in New York for the United Nations General Assembly meeting this week, nothing has really changed — and I’m not just referring to Iran’s state doctrine of Holocaust denial, about which Rouhani, when asked by NBC News’ Ann Curry whether he believed that the slaughter of 6 million Jews was a myth, replied, “I’m not a historian.”

For years, straight-faced Iranian diplomats have been turning up at meetings of the U.N. Security Council to offer assurances that their nuclear program is for peaceful purposes only, and that it abides by the terms of the Nuclear Non-Proliferation Treaty. Invariably, these announcements are compromised by reports from the International Atomic Energy Agency complaining of Iran’s refusal to cooperate, as well as the occasional discovery of yet another nuclear installation whose existence the Iranians simply forgot to disclose.

Take the underground uranium enrichment plant at Fordo, near the holy city of Qom. In 2009, the Iranians were forced to admit Fordo’s existence to the IAEA, after Western intelligence services exposed its activities. Last week, a report in the German magazine Der Spiegel that Rouhani was willing to close down Fordo in exchange for the lifting of international sanctions was quickly denied by Ali Akbar Salehi, the head of Iran’s Atomic Energy Organization. Then, in the same breath, Salehi added, “Iran is ready to enhance and strengthen engagement with the IAEA.”

You could put that another, more cynical way: Iran is doing what it has always done, using diplomatic engagement to buy time for its nuclear program. Even more important than Salehi, neither Ayatollah Ali Khamenei nor the IRGC have explicitly backed Rouhani’s conciliatory noises.

Should the Obama administration become heavily invested in a diplomatic track with Iran, skepticism and dismay will emanate from two main sources. First, the conservative Sunni monarchies in the Persian Gulf, who dread the thought that Shi’ite Iran might one day dangle a nuclear weapon over their heads. Second, Israel, which has poured scorn on Rouhani’s words, and for whom the following points remain non-negotiable: a complete halt to uranium enrichment, the removal of enriched uranium from Iran, the dismantling of underground nuclear facilities, and an end to any efforts to use plutonium to produce a nuclear bomb.

That’s why, when Khamenei speaks of Iran’s “main principles,” we should remind ourselves of ours. The real dilemma posed by nuclear weapons is not who owns them, but who is prepared to use them.

For decades, Israel’s nuclear weapons, which don’t officially exist, have served as a fundamental guarantor of regional peace and stability: If that vital military edge is removed by an Iranian bomb, the Middle East will be more perilous than it has ever been.

Just as worryingly, if Israel judges that any negotiations between the U.S. and Iran are going nowhere, Jerusalem could take the radical step of preemptively striking Iran’s nuclear facilities to eliminate what continues to be a very real existential threat.

Ultimately, the stakes are highest for the United States. Obama’s allergy to even limited military operations that don’t involve boots on the ground may well yield a much deadlier local conflict, in which the U.S. has little leverage.

If Obama cares about his legacy, he must do all he can to avoid such a scenario.

Ben Cohen

 is the Shillman Analyst for jns.org, where this essay originally appeared.