How can Europe withstand US secondary sanctions? In an era of unpredictable American foreign policy, this question has never been more important. The US’ re-imposition of secondary sanctions on Iran in May 2018 revealed Europe’s vulnerability to secondary sanctions and highlighted the limits to the EU’s ambitions of achieving strategic sovereignty. With geopolitical tensions rising, it is possible that the US could impose secondary sanctions on larger EU trading partners. In light of this possibility, this paper explores why secondary sanctions are so effective and offers concrete proposals to counter them.