18 May 2016

Based on an exercise which modelled violations of the Iran nuclear deal, this paper finds that the deal's framework enabled the transatlantic partners to remain united but domestic factors in the US and Europe could, in future, make this increasingly hard.


Xenia Wickett

Head, US and the Americas Programme; Dean, The Queen Elizabeth II Academy for Leadership in International Affairs

Dr Jacob Parakilas

Deputy Head, US and the Americas Programme


Signed agreement (Joint Comprehensive Plan Of Action) following E3/EU+3 negotiations, 14 July 2015 in Vienna, Austria. Photo: Thomas Imo/Photothek via Getty Images.
Signed agreement (Joint Comprehensive Plan Of Action) following E3/EU+3 negotiations, 14 July 2015 in Vienna, Austria. Photo via Getty Images.


  • Chatham House brought together 32 participants over a two-day period in February 2016 to discuss the US and European responses to a simulated scenario in which alleged actions by Iran threaten the sustainability of the nuclear deal. This was the second of four scenario roundtables (the first involved a conflict between China and Japan).
  • Despite the inherent challenges in the initial scenario the transatlantic partners in the simulation were able to retain a strong joint position in their negotiations with Iran throughout the scenario. The principal factor enabling the US and Europe to maintain their joint negotiating position was the framework of conditions provided by the Joint Comprehensive Plan of Action (JCPOA), which mandated specific actions, responses and timelines if events threatened the agreement. When in doubt, all parties in the simulation reverted to the agreed framework.
  • The Europeans in the simulation seemed to view any indirect consequences of the nuclear deal as mostly positive whereas the Americans largely saw the externalities as negative. Equally, the scenario showed Iran as having different approaches towards the US and Europe respectively: willing to engage with the latter, while keeping the former in the cold.
  • The greatest tensions occurred between EU member states, mainly in relation to differences over process rather than policy. Domestic factors in the US and Europe could, in the future, make maintaining a joint position towards Iran increasingly hard. In particular, potential stumbling blocks include immigration and social policies in response to the migration crisis in Europe; and, in the US, the significant political polarization around the E3/EU+3 deal.