In the EEZ, the supposed freedom of states to conduct military activities encounters the rights and duties of coastal states regarding conservation of marine resources and environmental preservation. This article focuses on the relationship between these two specific but not always compatible interests and asks: how should they be combined? Could international environmental law rules be interpreted as a limitation to the conduct of military activities in the EEZ? What are the concrete obligations of states to fulfil their environmental duties, and how far are they compatible with the conduct of other activities? The 'due diligence' obligation to protect the marine environment is interpreted as going further than the 'due regard' standard enshrined in Articles 56 and 58 of the LOSC. Accordingly, this article assumes that it is a positive obligation, implying specific consequences, such as the conduct of environmental impact assessments when the activity risks causing damage. Keywords exclusive economic zone (EEZ)-protection of the marine environment-military activities-pollution-due diligence obligation-1X