The EUNAVFOR MED anti-smuggling mission, Operation Sophia, ended in March 2020 and is largely viewed to have failed in its objective of ‘disrupting the business model’ of migrant smugglers in the Mediterranean region. The mission relied on purported enforcement powers in the 1982 United Nations Convention on the Law of the Sea and the 2000 Migrant Smuggling Protocol to seize and destroy stateless smuggling vessels on the high seas. Despite repeated claims to such powers by the European Union, neither treaty provides a strong jurisdictional basis for seizing stateless smuggling vessels outside territorial waters. However, ambiguous drafting in the Migrant Smuggling Protocol viably permits some claims to extraterritorial enforcement jurisdiction over stateless smuggling vessels on the high seas, and the European Union has relied on this ambiguity to tackle migrant smuggling. This article argues that the recent European Union anti-smuggling operations, most notably Operation Sophia, have reinterpreted the ambiguous term ‘appropriate measures’ in the Migrant Smuggling Protocol as permitting the states parties to exercise enforcement jurisdiction over stateless smuggling vessels at sea.