The nuclear deal reached with Iran in Geneva opens a new era in US-Iranian relations, even if the agreement is a tentative one. For the first time since Iran’s secret nuclear work was discovered in 2002, the two nations have outlined a way to allay fears the Islamic Republic is building nuclear weapons.

The Geneva agreement will almost certainly lead to changes in the region whether a final agreement is reached or not. All depends on how much of a nuclear threat Iran poses in the end, and whether countries like Turkey and Saudi Arabia feel they have to match Iran with nuclear military projects or capabilities of their own.

The deal marks the abandonment of the strategy which defined diplomacy with Iran starting in February 2003 with a visit to the Islamic Republic by then-UN nuclear watchdog chief Mohammed ElBaradei. The motto for this strategy, as enunciated by the United States, was “not one centrifuge turning,” meaning no uranium enrichment, the process which makes fuel for civilian reactors but also the explosive material for atom bombs. Enrichment, the producing of fissile matter, is the most difficult part in producing the bomb.

The Joint Plan of Action agreed to in Geneva says the comprehensive solution (to be reached within a year) would allow Iran to have an enrichment program, which had been a major obstacle to previous talks. There would be “practical limits and transparency measures to ensure the peaceful nature of the program ” according to the plan. Iran has thus won the green light to enrich, which it had required in any agreement.

But the joint plan deal is far from the whole story since it leaves current Iranian enrichment efforts intact and functioning though it does cap Iran’s nuclear work at current levels. It orders the elimination of Iran’s stockpile of 20 percent enriched uranium, closer to weapon-grade than the low, 3.5 percent enriched uranium declared to be for reactor fuel. Half of the 20 percent stockpile is to be blended down to the low level while the other half will be converted into oxide form for fuel for a research reactor. However, the centrifuges working at Fordow, a protected site buried within a mountain to be safe from air attack, will keep turning, enriching to low rather than medium level. The final reining in of Iran’s nuclear work remains to be negotiated.

The world reaction has so far been wary but accepting. Israel rejects the deal as an “historic mistake” but most analysts think an Israeli military attack against Iran is off the table until it becomes clear whether the negotiations are effective or not. Saudi Arabia, Iran’s main rival for influence and power in the Middle East, said in a government statement: “The agreement could be a first step towards a comprehensive solution for Iran’s nuclear program, if there are good intentions.” Since Saudi Arabia does not think the Islamic Republic has good intentions, its outlook is clear. And the ruling Saudi royalty has options. It could quietly back an Israeli attack, opening Saudi air space to allow the Jewish states’ warplanes to fly to Iran. Or it could move Saudi Arabia toward going nuclear, probably by buying nuclear weapons from Pakistan, a key ally and whose military atomic program Saudi Arabia helped finance. But for now all this is speculation. Meanwhile, Congress, suspicious of Iranian motives and actions, will apparently refrain from imposing further sanctions to give the joint plan a chance to work,

The United States had no choice but to strike this deal since Iran has done such a good job over the past decade of creating facts on the ground. Since 2003, when the UN watchdog International Atomic Energy Agency (IAEA) first visited Iran and saw a few research centrifuges spinning, the Islamic Republic has amassed an industrial level of enrichment with some 19,000 centrifuges installed and over 10,000 actually enriching. In talks with Iran both the United States and the IAEA, which is seeking greater access for inspections, felt they had reached an impasse due to the web of demands and counter-demands which made effective negotiation impossible. It was time to clear the table for a new start, which is what the joint plan represents.

The US advantage is that Iranian nuclear work will be limited for at least six months and subject to more intense monitoring than ever before. The Iranian advantage is that the deal leaves them with the technology to make atomic bombs.

The key to a final agreement will be how long it is to be effective and for how long it will cut Iran off from using for military purposes the nuclear knowledge and technology Iran has amassed.

Michael Adler, an expert on Iranian nuclear issues at the Woodrow Wilson International Center for Scholars, covered the issue for five years in Vienna, where he reported on the International Atomic Energy Agency.