I’m not in the least surprised that the “P5+1,” led by the United States and Iran, were able to agree to a time-buying “first step” nuclear agreement.

Back in January, when the newly-re-elected President Barack Obama was assembling his national security team, I argued that they seem to have been carefully chosen to pursue, above all, the Iran file.

And, in September, like others, I saw the potential for an interim agreement that doesn’t resolve the matter permanently but “buys everyone time.”

On Saturday night, it happened. Iran promised to stop advancement at its main nuclear facilities, including the heavy water plutonium plant under construction near Arak. Half its 20%-enriched uranium will be oxidized (rendering it unsuitable for weapons), and the other half will be downgraded to below 5% enrichment, which is only useful for non-military purposes.

The agreement permits Iran to continue to enrich uranium below 5%, but under scrutiny and with snap inspections. Iran has hailed this as a recognition of its so-called “right to enrich,” while the international community, especially the United States, notes that no such “right” is either explicitly or implicitly recognized in the agreement.

In exchange, Iran will get about $8 billion of its own money back in sanctions relief. Other sanctions are to be lifted in the petrochemical, automotive, and civilian aircraft sectors.

The agreement, assuming it is implemented in full, can be defended as having actually rolled back Iran’s approach toward nuclear weapons breakout capability without a shot being fired, at least by a few months. But it’s only defensible as a preliminary time-buying measure.

The largest, long-term issues, predictably enough, remain almost entirely unaddressed, including the quantity and quality of centrifuges Iran possesses and operates, what happens to its stockpiles of enriched uranium, a full accounting of everything Iran has done toward acquiring a nuclear weapon, and other relevant activities such as triggering and warhead devices.

On these bases, Israel and many members of the US Congress have expressed dismay, as has, more cautiously, Saudi Arabia. The deepest fear is that the US-Iranian engagement redraws the strategic landscape of the Middle East in an unpredictable and, for many, unsettling manner.

This raises three obvious questions.

First, will Iran see the opportunity for more aggressive action throughout the Middle East on the part of its clients and proxies in countries like Syria and Lebanon? Iran may calculate that it now has a freer hand simply because it has become a US partner in a grand experiment of extremely ambitious diplomacy. So a key question, which is disturbing the sleep of Israel, Arab states, and other observers throughout the world, is whether this limited but unmistakably historic agreement will make Iran and its proxies more regionally aggressive.

Second, will the United States be able to reassure its allies, particularly Saudi Arabia, Egypt, and others in the Arab world, that it remains an effective guarantor of their security in spite of this dramatic change? Israel, too, will be looking for reassurances. It is already attempting to deploy its considerable resources in Washington to push back against both the agreement and the general engagement with Iran.

Third, if US regional allies are not placated, will they seek to act as spoilers and try to scuttle the deal through their own direct and indirect interventions? Israel has the political resources to try to do this in the most direct manner possible: by influencing the mood and debate in the US Congress. But other American regional allies might feel forced to explore an expanded proxy, including unconventional and clandestine campaigns aimed at provoking the Iranians.

Is it possible that in seeking to preserve regional stability and contain the threat from Iran, the United States is actually and inadvertently creating conditions for a different kind of regional security deterioration? This probably depends more than anything else on how Washington explains exactly what it’s doing to its friends in the region, and how this approach doesn’t threaten their fundamental interests.

One final question: what happens in six months if the parties cannot agree to a broader deal that resolves all outstanding issues, as envisaged in the interim agreement? In the end, only Iran can really stop itself from going nuclear, given how far it has already come.

The most likely scenario, given that the principal aim of both sides is purchasing time, is either an extension of the existing agreement or additional interim agreements in which further steps are taken by both sides. However, the biggest bones of contention would be habitually postponed for another day, and another leadership, to grapple with.

If the parties can live with this general arrangement for six months – and want to continue to avoid a full-blown confrontation – then they can probably live with it, possibly with some further adjustments, for at least six years.