For six months, Iran will not enrich uranium beyond 5 per cent, dial down its stockpile of 25 per cent enriched uranium, stop the installation of new centrifuges, suspend the plutonium route and accept daily, deep inspections of its nuclear establishment. In return, it will enjoy token relief from sanctions - amounting to around $7 billion. During this period, negotiators from both sides will attempt to arrive at a substantive deal that will bridge the seemingly irreconcilable differences.
It would be a mistake, though, to take this interim nuclear deal at face value, for the Geneva agreement marks the end of a 34-year-long break in US-Iran relations. Washington had good reason to break off ties with Tehran after attacks on its embassy and citizens in the aftermath of Ayatollah Khomeini's Islamic revolution in 1979. By the turn of the millennium, though, reason had been largely supplanted by dogma, held in place by the interests of Washington's incumbent allies in West Asia. It didn't help when the George W Bush administration responded to Iranian overtures after 9/11 by placing Tehran in the odious basket of the "Axis of Evil".
Few in Washington will admit it, but this dogma cost the US dearly in the war in Afghanistan. It forced the US to rely on Pakistan, whose rent-seeking army was extracting financial and military rents even as it was actively undermining US interests. The US had to invest in a Northern Distribution Network, a long, circuitous and expensive supply route through the Eurasian landmass, and put up with odious dictatorships in the process. Had the US and Iran been on less antagonistic terms, the outcome of the Afghan war might have been quite different, and certainly less expensive.
It's not just Afghanistan. A US-Iran rapprochement will change the power equations animating almost all the conflicts in the region, with implications for the rest of the world.
That is why the breaking of ice between Iran and the US is important, and that is why it has rattled the countries of the region so much. As I wrote in these pages last Monday ("The Saudis, the Iranians and us", The Asian Balance, November 18), it is too early to identify what caused the US to change a three-decade old stand, but its plunging dependency on oil imports is an important factor. With the US liberated from the need, putting Saudi Arabia's interests up front, realists in Washington and Tehran could begin charting a course towards an eventual rapprochement.
It is tempting to see Iran's more accommodating approach as a result of the election of President Hassan Rouhani, who replaced the hardliner Mahmoud Ahmadinejad. There is also little doubt that Rouhani is a moderate who seeks to reconnect Iran with the international community. However, as we know now, US and Iranian diplomats began secret back channel meetings a few months before Iran's presidential elections in June. This indicates that the desire for engagement is not merely an initiative of a newly-elected moderate president, but has deeper roots within Tehran's establishment. It also means that we shouldn't expect Rouhani to be any less sensitive to the Ayatollah's red lines merely on account of his being a moderate.
Israel's concerns are real and Prime Minister Benjamin Netanyahu's strident condemnation of the deal is understandable. Yet, there are a range of outcomes of a US-Iran patch-up that enhance Israel's security. It may be such expectations that caused Israeli stock prices to rise to a record high the day after the deal was announced. In fact, important voices from within the country's military establishment have accepted that the deal might be better than the alternatives.
It is possible that Iran will follow the unhappy example of North Korea and use negotiations as a ruse to extract nuclear ransom from the West while continuing to build a bomb. Even if it does not it is highly unlikely that it will give up the nuclear option altogether. Rather, we might enter a period where two almost-nuclear weapons states are in a mutual deterrence relationship with an undeclared one: Iran a few months away from a bomb, Saudi Arabia a flight away and Israel merely an official announcement away.
Such a scenario bolsters the US' primacy in the region, at a time when Washington has the ability to act without being overly concerned about importing petroleum. How future US governments will use this power remains to be seen: solving West Asia's complex, interlocking problems is not going to be any easier merely because the geopolitical balance changes.
The opening made in Geneva may yet be wrecked by the rich and powerful beneficiaries of the status quo. That will still not change the fact that the ice is now irrevocably broken, and more attempts at rapprochement can be made if the current one fails.
The writer is co-founder and director of the Takshashila Institution, an independent think tank