The election of a new president in the US always has wide-ranging implications for the balance of power in the Middle East. But the shock result of Republican candidate Donald Trump defeating veteran politician Hilary Clinton on 8 November adds a new level of uncertainty to the US’ role as the most powerful external actor in the regional politics.

Nowhere is this more relevant than the relationship between the US and Iran, which thawed somewhat during President Barack Obama’s second term, culminating in the signing of a multi-lateral deal in January to relieve the Islamic Republic of nuclear-related sanctions.

The nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA), faced strong opposition from conservative politicians in both Tehran and Washington and was widely unpopular within the newly-empowered US Republican party.

During his election campaign Donald Trump called the JCPOA the “worst deal ever negotiated”, casting doubts over whether the agreement can survive the president-elect’s first four-year term. In October, Vice President-Elect Mike Pence promised the Trump Administration would “rip up the Iran deal”.

However, as with many of Trump’s most controversial election pledges, it is possible the incoming US leadership may take a more pragmatic approach when faced with the wide-ranging global implications of such an action.

Douglas Maag, senior counsel at law firm Clyde & Co, warned in a note on 11 November that US sanctions relief could change quickly when a Trump administration takes office and could change on its very first day.

“There are no legal teeth to the JCPOA. In essence, it provides that the consequence of a party’s failure to abide by its terms is that the other party becomes free to disregard its terms,” said Maag.

“Thus, if the Trump Administration takes the view that the JCPOA is not in the best interests of the US policy goals, it will be free to reverse some or all of the sanctions relief provided by the Obama Administration,” he added.

The question is whether Trump will feel the need to follow up his rhetoric by reinforcing sanctions against Iran, considering the adverse fallout from the US’ allies in Europe who have committed to the terms of the agreement.

Nazanin Soroush, senior analyst at US-based consultancy IHS, has looked at several possible Trump stances on the JCPOA based on comments during his campaign, ranging from dismantling the agreement or renegotiating it, to rigorously implementing it.

“All three could pose significant risks to the JCPOA,” said Soroush. “Even if the US did not actively pursue the JCPOA’s breakdown, the Republican Party’s opposition to the agreement would mean that a Trump Administration would be unlikely to actively promote its implementation.”

“This would risk suppressing appetite for foreign investment and resumption of European business ties with Iran. This would risk a reversal of Iranian calculations on the benefits of sanctions relief and increase the risk of Iranian nuclear non-compliance beyond the one-year outlook,” she added.

Rigorous implementation of the deal would risk reducing, if not eliminating, any room for resolving technical issues or minor non-compliance, says Soroush. For instance the International Atomic Energy Agency (IAEA), the international nuclear watchdog monitoring Iranian nuclear compliance, said that Iran had exceeded Iranian heavy water supply by 0.1 tonne on 9 November, although Iran was expected to ship five tonnes out of the country in a few days.

Strict implementation of minor issues such as this could quickly result in the breakdown of the JCPOA without the new US administration taking an official line to scrapping the deal.

While the terms of the JCPOA offer little sanctions relief to US individuals and companies, it has allowed significantly more freedom for non-US entities doing business with Iran. This includes waiving much of the US sanctions apparatus targeting non-US entities dealing with Iran’s energy, shipping, financial, shipbuilding and automotive sectors, port operators, as well as trade in several highly-traded commodities.

The implementation of the JCPOA kick-started a wave of memorandums of understanding (MoU) signed between Iran and European and Asian companies to pursue new projects in Iran across various sectors.

In November French energy group Total and China National Petroleum Corporation (CNPC) signed a heads of agreement (HoA) with National Iranian Oil Company (NIOC) to develop phase 11 of the South Pars offshore gas field; a project both companies had previously exited under sanctions.

The phase 11 scheme on the world’s largest gas field will have the capacity to produce 1.8 billion cubic feet a day (cf/d) to be fed into Iran’s gas network. Total could run the risk of breaching US sanctions should they be strictly reinforced by a Trump Administration.

However Philippe Sauquet, head of gas, renewables and power at Total, was cited as saying by Reuters in November that “the election that took place in the US does not change anything”.

Jason Tuvey, Middle East economist at Capital Economics, says that Trump’s opposition to the JCPOA appears to be contradictory to his wider views on the Middle East.

“Trump’s disapproval of the Iran deal is inconsistent with his hint of greater cooperation with Russia in Syria. After all, such a move would signal that the US is willing to tolerate Syrian President Bashar al-Assad staying in power, at least in the near-term. Crucially, Al-Assad is strongly allied to both Russia and Iran,” said Tuvey.

“Given Trump’s lack of foreign policy experience and focus on domestic policy issues, we will probably have to await further appointments to his team before we are able to fully judge how his administration will approach the Middle East,” he added.

Trump’s choice for secretary of state will be key in shaping the incoming president’s foreign policy strategy in the region. One of the favourites for the role, John Bolton, said in November that the only long-term solution for Iran is regime change.

Other potential candidates such as Mitt Romney and Rudolph Giuliani may take a relatively more pragmatic approach to handling Iran and the JCPOA.