The mood music from Almaty over the past few days hit a decidedly high note. Iran called the two-day talks in Kazakhstan a "turning point" in the dispute over its nuclear programme, while the United States was a bit more cautious, but did back a plan offering some relief on sanctions. After months of gloomy prognostications that talks would stall ahead of Iranian elections in June, the pleasant tone was an unexpected surprise.
Experience has shown, however, that one step forward in these negotiations is often followed by two steps back.
Iran has an unfortunate record of inconsistency in this dispute over the past decade. In 2009, for example, a proposal to swap uranium fuel stock - and thus address a key concern about Iran's domestic enrichment, which might be adapted to a weapons programme - broke down after Iranian negotiators returned home.
It is often domestic politics, rather than the niceties of international negotiations, that steer Iran's behaviour. While Supreme Leader Ayatollah Ali Khamenei has the whip hand in foreign policy, Tehran's tumultuous political rivalries make coherent policy difficult, and expose any sign of weakness as a career liability.
Iran's politicians have to be seen to be negotiating from a position of strength. This is, of course, a fiction. Sanctions are biting deeply into the economy, with an expected 40 per cent drop in oil revenues this year. In the worse-case scenario, Iran could face the overwhelming military might of the United States and its allies. Washington and other members of the P5+1 negotiating team have room to appear generous.
The deal proposed in Almaty would ease restrictions on Iran's energy exports, in return for Iran's commitment to cease enriching uranium to 20 per cent purity, which is used in healthcare but is also more easily converted into material that can be used in a weapon. If the two sides could strike that deal it would be an important, although reversible, first step.
Tehran still insists that its nuclear programme is solely for civilian purposes, to which it has a right. In truth, there is conclusive evidence that scientists are working towards a "break out" capability, at which point Iran could assemble a nuclear weapon in a relatively short time.
Sanctions were designed to prevent that weapon from ever being built, not to punish the Iranian people or achieve regime change. At the next round of talks, negotiators might want to offer further carrots to their Iranian counterparts. Let Tehran have its pretence of "negotiating from strength" to reach a deal that benefits all parties involved.