This article aims to examine factors influencing the development of international environmental cooperation and the roles of particular actors participating in environmental cooperation. In general, the majority of international actors agree with the importance of environmental protection but demonstrate different visions in terms of necessary measures. The final result depends on their capability to find common ground. It is assumed that the EU, with its strong environmental policy, realizes the importance of transborder coordination of environmental measures and tries to promote environmental cooperation. Russia was a serious challenge to the EU in terms of environmental security due to its geographic proximity, its severe environmental problems, and its harmful influence over environmental situation in the EU member states. The EU policy towards Russia demonstrates how the EU promotes environmental cooperation and ensures improvement of the environmental situation in the neighboring states. This paper will answer the following research questions: what factors determine the motivation of international actors participating in environmental cooperation; how the EU environmental traditions and decision-making procedures influence its external environmental activities; and how the EU tries to influence Russian environmental policy.