It won't be easy to revive an agreement that took years to strike and was ruthlessly sabotaged shortly thereafter, but US President-elect Joe Biden has pledged to do it. Iran has welcomed his intent.

Earlier this week, Iranian President Hassan Rouhani said his country would return to compliance with the nuclear deal, known as the Joint Comprehensive Plan of Action or JCPOA, within an hour of the US doing so. But that might not be enough. 

There is a chance that the United States and European powers ask for more. They may expect Iran to negotiate over its controversial missile program and its regional support for non-state actors — which the US and Europe see as destabilizing policies. Iranian officials have said they would only consider negotiating these concerns with their Gulf neighbors.

If this strife persists, attempts to resurrect the nuclear deal are bound to fail. 

The non-nuclear spirit of the nuclear deal

"Iran is not living up to the spirit of the [nuclear] deal" — US President Donald Trump made this remark almost every time he imposed a new sanction on Iran. His officials hammered home the narrative that the nuclear deal was a failure because it did not moderate Iran's actions in other areas. 

"Instead of killing the agreement, [Trump] could have built on it to address other concerns," says Kelsey Davenport, director for nonproliferation policy at the Arms Control Association, a US-based nonpartisan organization.

But he did not. Trump repeatedly said he wanted a new deal with Iran whenever he spoke, one that would cover US allies' concerns. Still, as Davenport notes, he did not have a viable strategy to replace the JCPOA.

Now, with Biden indicating the US will rejoin the agreement, calls for a new accord are growing. 

One voice making such calls belongs to German Foreign Minister Heiko Maas. In a recent interview with the weekly magazine Der Spiegel, Maas said: "A return to the previous agreement will not suffice anyway. There will have to be a kind of 'nuclear agreement plus.'"

In addition to Germany, France and the UK have also signaled support for a new deal. In a statement released in early December, the three European parties to the nuclear deal, known as the E3, welcomed "a diplomatic path to address wider concerns with Iran." On Thursday, the head of UN atomic watchdog IAEA, Rafael Grossi, endorsed their approach by saying: "I cannot imagine that they are going simply to say, 'We are back to square one' because square one is no longer there."

Pushing Iran for more is a tall order, according to Ellie Geranmayeh, an expert on the JCPOA at the European Council on Foreign Relations (ECFR): "The only way to pivot towards further negotiations with Iran is to first set a precedent of implementing the nuclear agreement and building confidence within the Iranian political establishment that they can actually get deals with the west in sustainable and durable ways that benefit Iran, too."

"Skipping over the 2015 nuclear deal and proposing a wider set of terms and a bigger deal, which Iranians were never willing to accept, even under Trump, is not going to be feasible," Geranmayeh says.

Even though the ‘maximum pressure' campaign failed to bring results, some Trump officials suggest Biden can take advantage of it. US Special Representative for Iran and Venezuela Elliott Abrams is one of those currently in the White House who believe the pressure campaign has inflicted huge pain on Iran and that Biden should use it to get a better bargain: "We have great leverage —  let us use it," he said in a webinar discussion put on by the United Against Nuclear Iran group this week.

On the contrary, Davenport sees the scenario facing Biden as being similar to pre-JCPOA negotiations: "The United States must first neutralize the growing risk posed by Iran's violations of the nuclear deal, restore confidence in US credibility by rejoining the accord, and then pursue talks to address these critical issues that fall outside the parameters of the [nuclear] deal."

Iran: 'Neighbors only' follow-up negotiations

So far¨, Iran has rejected adding any further issues to the agreement. "We will not renegotiate a deal which we [already] negotiated," said Iranian Foreign Minister Javad Zarif in November at a Rome policy conference. 

Iran sees its ballistic missile programs as its principal defense deterrent. Iranian officials often weigh the relatively large military expenditures of their neighbors against Iran's sanctioned arms and aviation industry. Unless other states in the region agree to the same restraints, Tehran is unwilling to make concessions.

Tehran's solution for ending the deadlock is a regional dialogue — without world powers. Iran's proposal, the "Hormuz Peace Endeavor" or HOPE, invites its neighbors to discuss their regional security concerns, as Foreign Minister Javad Zarif has written. In lieu of direct involvement of world powers, HOPE calls for a higher international body, such as the UN Security Council, to endorse the outcomes of the talks.

Iran's HOPE might not be entirely realistic. Western powers are the main providers of military and defense support to the Gulf countries and cannot be excluded from the talks. Plus, in Davenport's view, "Addressing Iran's destabilizing regional activities requires talks with both countries in the Middle East and world powers."

However, Iran's proposal could be a starting point for a much-needed dialogue without which the nuclear deal will be ineffective. "To provide further assurance that Iran will not pursue nuclear weapons in the future, it is important to address the underlying root causes that might push Tehran to decide that the benefits of nuclear weapons outweigh the costs," Davenport says.

The Middle East has changed a lot since the nuclear deal was signed. The United Arab Emirates and Bahrain, two of Iran's Arab neighbors, have normalized relations with Israel, and Israel is perceived to have been behind several attacks on Iran. Relations are sour. Discussing security issues requires a high level of trust, probably much higher than what Iran, its regional rivals and the west can muster.

Turning the clock back to 2015 is impossible. But if diplomacy fails again, arms proliferation and the collapse of Iran's moribund economy might follow. That, in turn, could lead to serious security concerns for the Middle East and the world, more serious than the current ones.