In the end, days of feverish diplomatic talks could not erase decades of hostility: US Secretary of State John Kerry and his Iranian counterpart Mohammad Javad Zarif failed in their attempt to reach a historic deal which would have ended Iran's international isolation in return for the abandonment of the country's quest to acquire nuclear weapons.
Theoretically, this is not a disaster. Monday's missed deadline was always artificial: All that has happened is that an interim agreement reached last year to freeze much of Iran's nuclear activity in return for the lifting of some of the sanctions will now be extended for a further seven months.
The negotiators - the United States, Britain, China, France, Germany and Russia on the one hand, and Iran on the other - are determined to continue.
And although Mr Kerry readily admitted that "these talks are not going to get any easier just because we extend them", he did point out that the negotiators have "earned the benefit of the doubt". In short, everything is still recoverable.
Still, the political setback is considerable, since all the historic precedents indicate that, once a real chance for a deal is missed in the Middle East, the opportunity seldom endures or returns.
The Americans had proposed a deal to limit to 4,500 the number of the centrifuges which Iran would be allowed to retain to enrich uranium, far below what a country needs to produce the ingredients for a nuclear bomb.
The US also promised that, if Iran accepted an intrusive system of international inspections to check that the deal's provisions were respected, the sanctions devastating the Iranian economy would be gradually lifted.
Mr Kerry spared no effort to impress upon the Iranians that this was the best offer they would ever get: He repeatedly warned Iranian Foreign Minister Zarif that the new, Republican-dominated US Senate which will start working in January is guaranteed to be tougher.
This message was also reinforced in a private letter from President Barack Obama to Ayatollah Ali Khamenei, Iran's supreme leader and the man who has the final word in such matters.
Ultimately, however, the Iranians did not budge: They wanted to be allowed to retain a far higher number of centrifuges, baulked at the intrusive nature of the proposed inspections and demanded the immediate lifting of sanctions.
Predicting prospects for the future now depends on understanding why the Iranians risked this breakdown in negotiations.
One interpretation is that, in the time-honoured custom of the Middle East, Ayatollah Khamenei opted to haggle for further concessions from the United States.
Yet a more ominous but probably more accurate interpretation of Iran's behaviour is that Ayatollah Khamenei and his hard-line associates believe that the US is simply weak, and that the US needs Iran more than the Iranians need the Americans.
The assumption in Teheran is that Washington would require Iranian cooperation in defeating the Islamic State in Iraq and Syria (ISIS) terrorist movement now tearing Iraq apart; Iran is also indispensable to any solution in Syria or Lebanon.
A "package deal" which in return for this cooperation allows Iran to become a "threshold nuclear state" - a country which has the capability to deploy a nuclear weapon without actually producing one - may be what Ayatollah Khamenei is aiming for.
But there is no way a Republican-controlled Congress in Washington would swallow such a deal, either explicitly or implicitly: Leading Republican senator Marco Rubio has already called for fresh sanctions, a "return to the pressure track that originally brought Iran to the table".
Nor would this work with the United States' regional allies: Notably, and for the first time ever, the Saudi foreign minister was present at the latest round of talks, a clear indication that the US is anxious to reassure its friends that their security interests are not up for bartering.
And although the US can do with Iranian help, this is neither necessary nor urgent: The tide may already be turning against the ISIS terrorists in Iraq.
By refusing to bend, Ayatollah Khamenei no doubt recalls his younger days as a revolutionary, when Iran defied then-US president Jimmy Carter with impunity; Ayatollah Khamenei probably believes he can repeat this feat today.
But the Jimmy Carter episode is also haunting Mr Obama as an example to avoid. And betting on US decline is something many other Middle East leaders have attempted, usually with little success.
The rejection of a nuclear deal could yet turn out to be Iran's costliest mistake.
This article was first published on November 26, 2014.
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