The aim of the study presented in this paper is a framework offering an integrated energy security assessment, based on different approaches. We consider a novel methodology as an integrated framework of different types of analyses and methods of energy security assessment towards the application for energy security level forecasting. A framework is needed for the integration of methods, capable of viewing the problem from different perspectives and suitable for coping with the high complexity of the issue to be solved. Key ideas and strengths of different methods were employed towards forecasting of energy security level in the future in order to evaluate the impact of new development projects in the energy system in terms of energy security assurance. Two different methods for the forecasting of energy security level considering various energy system development scenarios are proposed in this paper: the update of energy Security level by using Bayesian method and the solution of a system of random differential equations. The implementation of the developed framework is demonstrated in a particular case study for Lithuania. The application of methodology for energy security level forecast highlights the impact of different energy development projects on energy security. (C) 2017 Elsevier Ltd. All rights reserved.