European nuclear diplomacy with Iran has always had a transatlantic dimension at its core. Facilitating US–Iranian engagement is instrumental to securing European long-term interests in supporting the non-proliferation regime and preventing a major military confrontation in the Gulf. Over the years the Europeans have made a number of tactical adjustments in pursuit of this strategic goal. They succeeded in turning initial transatlantic divergence under Bush into a fairly solid transatlantic consensus under Obama, when the Iran nuclear deal or JCPOA was signed. After Trump pulled the US out of the deal, Europe fell back on conflict management, which was barely enough to keep the JCPOA on life support. With Biden the pendulum has shifted back to transatlantic re-engagement, with a view to revive the nuclear deal. Convergence with the US remains indispensable, but it may require a degree of leverage over Washington that Europe has lost.
Read more here.