In Greek mythology, Cassandra was the daughter of King Priam and Queen Hecuba.

When this reputedly beautiful girl refused the romantic overture of Apollo, he placed a lifelong curse on her. While she possessed the prophetic ability to see the future, no one would believe her.

Thus, for example, she foresaw the destruction of Troy, including the use of the Trojan Horse, but, as a result of the curse, her pleas went unheeded. The ensuing tragedy proved her forecasting ability.

Is Israel today the world’s Cassandra? And are President Hassan Rohani and Foreign Minister Javad Zarif the Iranian Trojan Horse?

Israel succeeded in helping galvanize the world’s attention to the imminent threat of the Iranian nuclear program. Yet now there are new faces in Iranian public diplomacy, figures who complicate a tableau made starkly simple by the combative and offensive former president, Mahmoud Ahmadinejad.

With Ahmadinejad in power, it all seemed so clear.

Calling for a world without Israel, denying the Holocaust, claiming there are no homosexuals in his country, and crowing that Iranian women are the world’s freest, made it hard for just about anyone outside Caracas, Pyongyang, or Damascus to see him as a credible interlocutor.

Meanwhile, Iran’s centrifuges kept spinning and improving in sophistication, missile development proceeded apace, and Iranian negotiators skillfully bought time without delivering anything tangible in return.

But now Rouhani and Zarif are on the move, employing social media, their fluency in English, initiating public appearances galore, and participating in marathon diplomacy to send a message of engagement, openness, and moderation.

And, no doubt, they sense they have at least one other card to play – the belief that the West really does not have the appetite for confrontation with Iran, with its built-in risk of military conflict.

The Syria saga may lend credence to this view, at least in their eyes.

The British Parliament unprecedentedly repudiated its prime minister, forcing David Cameron to remove the U.K. from those nations threatening military retaliation against Syria for its use of chemical weapons.

And the American posture revealed a public strongly opposed to U.S. action, a Congress deeply divided on an authorizing resolution, and a president who seemed to some to be waffling in defending the “red line” he had set regarding Syria.

Now along come the newly minted Iranians and the rush to sit down with them, host them, and discuss symbolic public handshakes.

To be sure, it’s all accompanied by the Reaganesque language of “trust but verify,” but there almost seems an audible sigh of relief in some Western capitals that a new way can be found to de-escalate the growing clash, pull back from the brink, and negotiate as reasonable people.

As all this unfolds in New York during the opening of this year’s UN General Assembly, as well as across Europe, one voice strives to be heard, carrying a discordant message – one that is not entirely welcome and that is seen, perhaps, as overly belligerent.

That voice, of course, is Israel’s.

Be wary, say Israeli officials. Learn from the past, whether it is Munich in 1938 or Pyongyang in 2005. Measure Iranian policy not by seductive words, but rather by concrete deeds. If the Natanz, Qom and Fordow sites are still busy enriching uranium, it doesn’t matter what Rohani and Zarif say – or how they say it. To be drawn into their trap runs the risk of emerging when it’s too late, and Iran has reached the point of no return.

But the problem is that if Israel turns out to be Cassandra, the world may not listen – and Israel is then left with the unenviable question of what to do next.

As it is, Israel was the only one of 193 UN member states not to sit in the hall and listen to Rohani’s speech.

Did that help or hurt Israel to make its case? Some would argue it helped by stressing the danger and willingness to act, even if alone. Others, however, would say that Israel only demonstrated its unwillingness to hear the message, even if Rohani turns out to be, say, the next Mikhail Gorbachev.

So, unless Israel wants to continue to find itself largely alone on the world stage, it will have to find new ways to make its case, so that it is not just talking to itself and its supporters. Simply implying, for instance, that anyone who sits down with Rohani is a modern-day Neville Chamberlain or Édouard Daladier won’t do the trick.

To the contrary, it will only give offense and alienate. There are more effective and less shrill ways of making the case for caution, vigilance, and strength.

Otherwise, Israel could end up becoming the 21st century Cassandra, should it turn out to be right about the emptiness of the new Iranian spin – and the goal for which those centrifuges are spinning.

David Harris is the executive director of American Jewish Committee (AJC).