Modern trends in international relations, a growing deficit of energy resources, raising awareness of unsustainability of the existing model of consumption, as well as the negative impact of the greenhouse effect on climate changes, all bring home the issue of adopting new strategies and introduction of structural changes in the field of energy policy. The paper offers a diachronic analysis of the situation regarding energy policy in international relations through considerations of global challenges in energy security, focusing in particular on the challenges of energy security of the European Union. New challenges, especially the climate changes, but also resurfacing of the old ones, such as supply security and increasing global competition, have contributed to defining a common energy policy based on a completely operational internal energy market of the European Union. Current energy policy of the European Union is aimed at encouraging the development of low energy consumption economies, mitigating climate changes, as well as ensuring a higher level of energy security by integrating the European Union energy market and developing energy infrastructure.