Europe's dependency on non-EU countries' energy supply is sharply increasing. Recently, sudden supply disruption caused by international disputes outside the EU have created serious problems for some EU countries and raised concern in many others. In these situations, it is highly desirable to have a tool to assess possible outcomes of supply disruptions. This paper presents a newly developed model, MC-GENERCIS, aimed to assess the robustness of the EU transnational gas transmission system during both normal and special operating conditions, including high-demand situations and/or a supply shortage. The model has a country-by-country resolution and examines all possible dispatching choices of national TSOs on the basis of a probabilistic MonteCarlo approach. The preliminary validation of the model through its application to the "normal" conditions for the winter 2008-2009 and to the recent supply disruption involving Ukrainian gas transit is also described. (C) 2010 Elsevier Ltd. All rights reserved.