The changing security environment in Eastern Europe has increased the strategic importance of road infrastructure for national resilience, civilian protection, and allied military mobility. Lithuania occupies a critical position on NATO's north eastern flank, where a limited number of strategic road corridors simultaneously support domestic mobility, freight transport, civilian evacuation, and allied reinforcement. This study assesses the resilience of Lithuania's national road network under four military threat scenarios: blockade of the Suwałki Corridor and attacks from Kaliningrad Oblast, Belarusian territory, and the Latvian direction. The methodological framework combines structured evidence synthesis from public transport and infrastructure data, strategic and policy documents, and scientific literature with spatial road network assessment, scenario analysis, and multicriteria vulnerability scoring. The Scenario Severity Index identified the Belarusian scenario as the most severe, scoring 24 of 25 points and reaching 96 percent. The Suwałki Corridor and Kaliningrad scenarios each reached 80 percent, while the Latvian direction scenario reached 64 percent. The analysis identified A1, A5, the Vilnius to Kaunas axis, the Kaunas transport node, and strategic connections with Poland and Latvia as the most critical network elements. The findings show that simultaneous civilian evacuation and military movements may constrain road functionality even without direct infrastructure loss. Nationally coordinated corridor based resilience management and unified civil military traffic coordination are therefore required. The results also provide a structured vulnerability evidence base for the future development of the National Transport Mobilization Index.