This research examines how the Russia-Ukraine conflict has challenged the liberal institutional order that has governed international relations since 1991. Using realism theoretical frameworks, the study analyzes the limitations of international law in regulating the behavior of great powers when core security interests are threatened. The Russia-Ukraine conflict demonstrates how traditional geopolitical considerations can override institutional constraints despite decades of economic interdependence. Through analysis of Ukraine's geostrategic position and Russia's security perceptions, the study demonstrates the continued relevance of realism in explaining power dynamics in the international system. Using Vietnam as a case study, the research proposes strategic policy recommendations for small states navigating geopolitically sensitive positions amid great power competition. Finally, this study contributes to international relations discourse by illustrating the enduring explanatory power of realism while offering practical foreign policy approaches for small states seeking to maintain autonomy in an increasingly competitive great power environment.