In 2003, a “perfect storm” of intersecting developments saw Tehran caught with one hand in the nuclear weapon cookie jar (secretly enriching uranium), despite having joined the Nuclear Non-Proliferation Treaty and given assurances that it would do no such thing. The Iranian regime was humiliated.

India and Pakistan had endured sustained condemnation when they declared their nuclear-armed status via a blizzard of tests in 1998, but they were known proliferation risks and had declined to join the NPT. Even the DPRK—not a state that anyone wants to be compared to—had gone through the formality of withdrawing from the NPT in April 2003, to (redundantly) signal its intent to pursue a nuclear weapon capability.

Iran opted to bluff its way through. Tehran steadfastly denied that it had an obligation to restore confidence in its compliance with the NPT. It insisted that everything the IAEA could discover was consistent with its intention to build a substantial network of nuclear power stations. It maintained that it was also exercising its rights under the NPT to acquire its own capacities to fuel its future reactors with enriched uranium and (potentially) plutonium. For its part, the US insisted that Iran had to get out of the enrichment business.

Twelve years later, on April 2, 2015, negotiators from China, France, Germany, Russian, America and Iran announced agreement on a Joint Comprehensive Plan of Action (JCPOA) concerning special arrangements to bolster confidence that Iran’s nuclear program is exclusively peaceful in intent and that it has no aspirations to acquire nuclear weapons. The JCPOA—details of which can be found here—is commendably comprehensive, addressing both the enriched uranium and plutonium paths to the fissile core of a nuclear weapon.

Enrichment capacity will be cut by two-thirds and technological development precluded for 10 years; stocks of low-enriched uranium are set to be reduced to token levels for 15 years; the IAEA will have enhanced visibility of and access to Iranian nuclear facilities to verify compliance with the new agreement.

The central bargain may well have been Iran’s acceptance of the need for “special arrangements” with the US conceding retention of an enrichment capacity, albeit on that’s circumscribed. If one looks at the key players, the regional context over recent decades and the broader global developments on the nuclear weapon front, easily the most surprising thing about this agreement is that it happened at all.

Support for the agreement, generally on arms control grounds, has been qualified while opposition to it has been markedly more absolute and trenchant. The Australian’s Greg Sheridan  called the deal “a dismal outcome for the world” as the restraints on Iran’s nuclear activities are either reversible or expire after 10–15 years while economic sanctions, once lifted, are unlikely to be re-imposed if Iran misbehaves.

Henry Kissinger and George Shultz share Sheridan’s disappointment, contending that the deal won’t stop Iran’s nuclear potential from stoking anxieties in the Arab world that, in the final analysis, Washington will have to deal with. They stress that Iranian–Arab rivalries have been shaped over millennia, making a decade of restraint of little consequence to Arab states.

Coming to a comfortable judgement on the utility of this deal is not easy. But most criticisms fail to consider what alternative courses of action were both feasible and likely to deliver better outcomes. If abandoning enrichment had been made non-negotiable, the options might have been continual intensification of economic sanctions—with the mounting risk that Russia and China would trigger either a break in the ranks—or the use of force.

America still has unique capacities to attract support and make things happen, but it’s relative power and room for maneuver, including on the home front, isn’t what it used to be. Even the use of force could only delay an Iran determined to acquire nuclear weapons. The fact is that the character of the non-proliferation challenge has been transformed.

Acquiring nuclear weapons is not a trivial undertaking but neither is it any longer a massive, complex challenge fraught with uncertainty and the risk of failure. The decision of whether Iran becomes a nuclear-armed state rests entirely in their hands, just as it does for a significant number of other countries around the world, including Australia.

If Iran remains a non-nuclear weapons state indefinitely, it’ll be because that’s its preference. Many factors (and states) will shape the outcome on this question, not just Washington and not just this agreement.

The JCPOA is an interim agreement. Many crucial details—not least concerning the verification arrangements and the lifting of sanctions—still have to be thought through, agreed, and expressed in clear language before June 30, 2015.

Iran’s supreme leader has already tried to pre-empt the process, signaling that he’s prepared to walk away from the deal if any agreement on June 30 doesn’t provide for the immediate and complete lifting of sanctions. But if a deal can be finalized without distorting the integrity of the package, it should make a positive difference. Certainly, it is hard to see how it would make things worse.

This piece first appeared in the Australian Strategic Policy Institute’s (ASPI) blog The Strategist here.