A major priority of whoever wins the US presidential election will be to set or reset relations with Iran. Whichever way it goes, the result will have huge implications for regional security.

For both Donald Trump and Joe Biden, three primary issues will be on the agenda: stopping Iran from attaining the capability to develop nuclear weapons; limiting Iran’s development of ballistic missiles, including, potentially, nuclear-capable missiles; and stopping Iran’s regional ‘destabilisation’, including support for terrorism.

However, Trump and Biden differ significantly on what they see as a satisfactory outcome and on how they think they can achieve it. Trump’s aim is to renegotiate the Joint Comprehensive Plan of Action, a nuclear-only agreement, or to seek a new agreement that covers all three issues. At the heart of any such agreement will be the 12 demands made by Secretary of State Mike Pompeo in May 2018. In essence, Trump’s strategy involves continuing confrontation.

Biden has rejected Trump’s path and would seek resolution though credible diplomacy. His preference is to rejoin a revised nuclear-only JCPOA and negotiate the other two issues separately. He will pursue a tough but ‘negotiable’ pathway that offers a notional win–win outcome.

Trump’s tactics are to force regime change in Iran, through a ‘maximum pressure’ campaign using isolation and comprehensive sanctions to create the level of extreme economic hardship necessary to drive the Iranians to the negotiating table. If that fails, his apparent intent is to precipitate sufficient public dissent to cause the overthrow of the regime, and then to negotiate a compliant policy with whoever takes over.

A re-elected Trump will likely seek to force the Iranians to negotiations early in 2021. Iran’s presidential elections are due in mid-2021, and the results of recent parliamentary elections suggest that President Hassan Rouhani, a moderate, who constitutionally cannot seek re-election, could be replaced by a hard-line conservative. Potentially, Rouhani might offer a better deal, if any deal with Trump were possible.

Trump appears to have accepted the likely potential consequences of continuing confrontation—significant civil unrest within Iran, or possible military conflict. And unless he radically changes his tactics, either could result.

Any significant domestic dissent that threatens Iran’s regime will be forcibly suppressed. In the worst case, if the Iranian regime loses control, there can be no takeover of government by an organised opposition—there is none. Destabilisation of Iran and its 83 million people would have dire consequences domestically, and regionally.

So too would armed conflict, which could ultimately involve other regional states and non-state actors such as Israel, Saudi Arabia, the United Arab Emirates, Iraq, Hezbollah and other pro- and anti-Iran proxies. While neither side wants war, one major concern is that such a conflict could be triggered unintentionally through miscalculation, especially if either side plans a pre-emptive strike strategy. If conflict occurs, Iranian nuclear facilities and missile bases and production facilities will almost certainly be primary US targets.

The Iranians will seek to avoid either outcome to protect their regime, but negotiations in these circumstances would entail humiliating public capitulation.

Biden’s diplomatic strategy, which has the support of the other JCPOA signatories (Britain, France, Germany, the EU, Russia, China and the UN) would also seek to draw on any residual goodwill and trust that might exist from the Barack Obama era to underpin negotiations, but the pickings will be thin.

The specifics of Biden’s negotiation tactics have not yet been disclosed.

Of the three major concerns, it’s likely that the missile issue will be the simplest to negotiate. In 2017, Iran’s Supreme Leader, Ayatollah Ali Khamenei, reportedly capped the range of his country’s ballistic missiles at 2,000 kilometres, which other Iranians have asserted provides an adequate regional defensive capability.

Iranians claim they don’t intend to develop intercontinental ballistic missiles or missiles able to carry nuclear weapons. They say they have no such weapons and don’t intend to acquire them. Iran also claims its missile capability poses a significantly lesser threat than the massive array of sophisticated weapons, including missiles, deployed against it by the US and its regional allies.

If Iran reaffirms these limitations on its missiles, and a deal is struck that limits the export of missiles—especially to Hezbollah, which Israel considers a direct threat—an agreement is potentially negotiable.

A renegotiated JCPOA could also deliver a notionally win–win situation if certain conditions were met.

Tehran would have to reaffirm its commitment under the JCPOA ‘that under no circumstances will Iran ever seek, develop or acquire any nuclear weapons’. Both sides would be obliged to agree on the nature and timing of revised sunset clauses, Iran would have to return to IAEA-verifiable limitations on uranium enrichment, and the US would have to lift all of Trump’s sanctions.

But it wouldn’t be that simple. Biden isn’t expected to lift all of Trump’s JCPOA sanctions at once. He’s likely to lift sufficient sanctions to give traction to a renegotiated JCPOA while selectively keeping some to provide the leverage necessary to influence Iran’s regional activities.

Although Biden hasn’t yet announced any broader Middle East peace plan, the circumstances are right and there is an urgency to do so. Like Trump, Biden faces the same time pressure to deal, at least initially, with a Rouhani government.

An innovative and ambitious peace plan could bring Iran and other regional stakeholders into the same tent to translate into action the numerous public commitments by each to peace, security and stability.

Biden could roll in all three issues as well as Rouhani’s 2019 Hormuz Peace Endeavor (HOPE), together with other regional initiatives, including the recent Abraham Accords. Such a plan would provide a live forum for Iran (and others) to demonstrate their willingness to cooperate and use influence with regional states and non-state actors to tailor constructive solutions to regional realities.

The challenges will be significant, as will the opportunities. The remaining sanctions could be lifted progressively as results emerge.

Pending the announcement of any such peace plan, it’s likely there’s been a back-channel dialogue between representatives of Biden and Rouhani exploring these issues. Building trust will be key for both parties.