GENEVA: The central riddle as we head to new talks here on Iran’s suspect nuclear program is that everything has changed, yet nothing has changed. Hopes have never been higher, but a deal is far from being done.

September brought us a surprising “Iranian spring” in the crisis over fears Tehran seeks the bomb. The foreign ministers of long-time adversaries Iran and the United States sat down for a 30-minute talk at the United Nations in New York that was the highest formal contact between the two states since the Islamic revolution in 1979. Iranian President Hassan Rouhani and US President Barack Obama took the contact to an even higher level when they chatted by telephone as Rouhani drove to the airport for his flight home.

This was prelude to what will happen here Tuesday and Wednesday when Iran meets with six major powers who seek guarantees that Tehran will not develop nuclear weapons. Negotiations have failed for over a decade. The crisis began in 2002 when Iran was caught hiding two major nuclear facilities, one to enrich uranium and the other which could produce plutonium. These have civilian power uses but are also the keys to the two ways of making the bomb.

The United States and its partners Britain, China, France, Germany and Russia want Iran to take a major step to reduce its nuclear capabilities and they want this step to be a confidence-building measure that would be the entry chip to talks, not the ticket to having sanctions against Iran lifted.

Iran, however, wants immediate and substantial relief from unprecedented sanctions which have crippled its economy by slashing its oil sales by over a half and shutting it out of international banking.

Nothing has really changed recently, except the atmospherics. Iran is ready to offer a suspension in enriching to the medium-level of almost 20 percent of the uranium isotope U-235, which is a key step to getting to weapon-grade of over 90 percent. But Iran wants significant sanctions relief in return. The US position, which officially remains the same, is that Iran’s first cut in its massive nuclear program which has amassed huge stockpiles of up to five-percent enriched uranium would only be a prelude to further concessions. Then talks would begin on dismantling the sanctions regime against it.

None of this may matter if the United States judges that the Iranian proposal expected here and the new tone and way of doing business of the Iranians inspires enough confidence to move quickly to sanctions relief.

Here’s how things could go well. Iran says it is ready to deal and US officials stress privately that they are too, but they first have to see “concrete steps” from Iran. In this scenario, the proposals do not matter. It is the horse-trading that would take place in this new atmosphere of confidence which could lead to a workable agreement. Iran for instance might be swayed by a US promise that it could keep enrichment, although reduced from its current level, at the end of the process.

But things could easily go poorly. Iran may offer too little to satisfy the United States. Or Iran may insist on what it calls “reciprocal”, simultaneous responses to its cuts. That would be farther than the United States and its partners would or could go in a first phase. Waivers of some sanctions but not outright abolition of sanctions laws might be the best Washington could do right away. Such timing issues have doomed talks in the past.

US officials caution against anyone reaching a final deal here. But if there’s no concrete progress then the “spring” brought by Rouhani may turn out to be nothing more than a groundhog moment in this endlessly fruitless diplomacy. That could mean time is running out for a peaceful settlement, with Iran amassing ever more nuclear capability that cuts the “break-out” time needed to make a bomb. Israel continues to argue that Iran is all talk and nothing has changed. All is in Iran’s hands now.