The term _Westphalian_ refers to the system of international order conventionally traced to the Peace of Westphalia in 1648, which concluded the Thirty Years’ War in Europe. The treaties signed at Münster and Osnabrück did not create a fully formed modern state system overnight, but they crystallised principles that would become foundational: territorial sovereignty, legal equality among states, and non-interference in domestic affairs. Before Westphalia, political authority in Europe was layered and overlapping. The Holy Roman Emperor, the Papacy, dynastic houses, city leagues, and emerging monarchies all exercised claims that cut across territorial boundaries. Allegiance was often personal or religious rather than strictly territorial. The devastation of the Thirty Years’ War, however, forced a pragmatic settlement. Political authority would henceforth be tied more clearly to defined territories. Rulers would determine the religion and governance of their own domains. External powers would recognise those boundaries. The “Westphalian order,” then, is shorthand for a world of sovereign states operating in an anarchical system — not chaotic, but lacking a higher governing authority. States are juridically equal, even if unequal in power. Their legitimacy rests on control within recognised borders. External interference in internal affairs is formally proscribed. Over the following centuries, particularly during the period of Euro-Atlantic ascendancy, this model was globalised. European empires exported the state system through colonisation and later decolonisation. Newly independent states in Asia, Africa, and the Middle East entered an international society structured around Westphalian norms: sovereignty, territorial integrity, diplomatic recognition, and legal equality. In the twentieth century, these principles were embedded in the United Nations Charter. The Five Principles of Peaceful Coexistence, articulated in the mid-twentieth century, can be read as a restatement of this Westphalian logic for a post-colonial world: mutual respect for sovereignty, non-aggression, non-interference, equality and mutual benefit, and peaceful coexistence. They reflect a desire — especially among states emerging from imperial domination — to stabilise a system in which formal sovereignty protects weaker states from external coercion. Yet the idea of “Westphalian” is partly mythologised. Historians note that intervention did not end in 1648, nor did religious politics disappear. Great powers continued to interfere in one another’s affairs when interests dictated. The system has always contained tension between legal equality and material hierarchy. In contemporary debate, invoking the Westphalian order often serves as a normative claim rather than a purely historical one. It signals support for sovereignty and restraint against universalist or interventionist doctrines. Critics of humanitarian intervention, regime change, and expansive alliance politics argue that such practices erode Westphalian norms. Supporters of liberal internationalism counter that strict non-interference can shield repression and that evolving norms — human rights, collective security — modify but do not abolish sovereignty. Thus, in the context of Kennan’s warning about perpetual preparation for war, the Westphalian concept represents a competing logic: stability through mutual restraint versus instability through anticipatory confrontation. If sovereignty is treated as conditional or subordinate to ideological alignment, the system moves away from its Westphalian foundations. Whether that shift represents moral progress or strategic overreach remains at the heart of contemporary geopolitical argument.