When Iran signed the Joint Comprehensive Plan of Action (JCPOA) in 2015, the administration of President Hassan Rouhani was pursuing a policy of restoring and expanding trade and investment relations with the European Union (EU). The bloc was viewed as a reliable source of investment and technology for Iran’s future development.

In fact, the EU had been the country’s largest trading partner until 2011, when it lost that position to China. This occurred in light of the sanctions imposed on Iran between 2010 and 2015, and especially the 2011 EU restrictions on Iranian oil exports...