The article furthers the debate on environmental security by highlighting the role of visual technologies such as satellite remote sensing in the construction of threats and risks. It provides a rereading of the critical literature on environmental security through the lens of Actor-Network Theory and argues for understanding environmental security as a form of ontological politics. A theoretical framework around the notion of visual assemblage is developed that accounts for the hybrid, socio-technical character of visual technologies like satellite remote sensing, and shows how these render environmental risks and threats visible, intelligible, and thereby governable. Equipped with this framework, the article traces the development of a visual assemblage of satellite remote sensing from the early days of the Cold War until today and reveals its close co-evolution with environmental security discourses and practices. Three major contemporary remote sensing projects are analyzed to reveal how this global visual assemblage enacts multiple versions of environmental security: as resilience of local populations and ecosystems, as a series of local risk factors that become manageable through market-based risk management, and through a ‘meteorology of security’ based on the collection, harmonization, and automated analysis of big (environmental) data from multiple sources.