This publication is the winner of the Admiral Castex 2025 prize. Admiral Castex’s prize, named after a French naval officer best known for his work as a naval theorist and his contributions to maritime strategy, aims to promote original and unique research into naval strategy.

There are several factors that could help navies mitigate those constraints:

• Increased reliance on multirole platforms for standard naval operations;
• Better burden-sharing between actors, allies and partners, navies and the civilian sector;
• Strategic integration of unmanned systems (UAVs, UUVs, USVs) to create mass.

The classic literature in naval and maritime strategy has long identified a strong relationship between the characteristics of naval forces and one of the main features of their political utility, namely protecting sea lines of communication in order to enable trade, and thus wealth. Alfred Thayer Mahan went so far as to argue that the core purpose of a navy is to enable maritime trade and economic growth. However, the modern maritime economy faces a range of threats that naval forces must confront: climate change, economic warfare, shadow fleet operations, the vulnerability of critical infrastructures, and illicit activities like piracy and illegal fishing.

In principle, the strategic practice of deterrence offers a cost-effective means to address these challenges. Yet, we argue that achieving deterrence against threats to the maritime economy is fraught with difficulties stemming from the very nature of naval power. Building on the conceptual literature on deterrence, we identify those challenges and explore how navies can effectively deter threats to the maritime economy. Ultimately, deterring threats to the maritime economy with naval platforms is difficult, but some steps can be taken to reduce the magnitude of the challenge.