Ensuring access to sustainable, affordable and clean energy sources is a top priority of the global energy agenda. It is reflected in the seventh goal of the UN Sustainable Development Agenda with the three dimensions of economic growth, social inclusion and environmental protection. The seventh goal is aimed at providing the sustainable development of energy systems whilst taking into account these dimensions. To assess the development trends of national energy systems within the framework of the global energy agenda, certain methods of quantitative measurement have acquired particular relevance. Approaches to assessing energy security mainly depend on the interpretation of the "energy security" concept. The main methods for the integrated assessment of the energy security of states are generally compiled by international organizations. An important indicator for the measurement of the sustainable development of energy systems is the Energy Tri-lemma Index, built within the framework of the "energy trilemma" concept. It allows quantifying the ability of states to ensure energy security, energy equity and environmental sustainability, taking into account the national context. Special attention is paid to the analysis of the energy systems of Russia, Kazakhstan and Armenia through the Energy Trilemma Index 2022. The studied countries actively participate in the integration processes in the Eurasian and post-Soviet space. Thus, the analysis of the Energy Trilemma Index 2022 allows us to become acquainted with the main trends of the energy sector development in the Eurasian space, exploring the conjuncture of energy markets and their main challenges. The study of the energy systems of Russia, Kazakhstan and Armenia through the energy trilemma index enables the identification the methodological significance of the index for assessing the sustainable development of national energy systems. The practical relevance of the index in the formation of the state energy policy for the sustainable development of the energy systems has also been emphasized.