The global defence industry is entering a new phase. For three decades after the Cold War, many countries treated defence as a necessary but controlled public expenditure. That assumption has changed. Continuous geopolitical tensions, the Russia–Ukraine war, conflict in West Asia, instability in the Indo-Pacific, cyber warfare, drone warfare, and supply-chain weaponisation have pushed governments to rethink defence not only as a military necessity but also as an industrial, technological, and strategic economic sector. According to SIPRI, global military expenditure reached US$2.718 trillion in 2024, rising 9.4% in real terms over 2023 the steepest annual rise since the end of the Cold War. More than 100 countries increased military spending, indicating that defence expansion is no longer confined to active war zones but has become a global policy trend. The defence industry must now be understood through three lenses: national security, industrial capability, and strategic autonomy. Governments are not simply buying weapons; they are trying to secure domestic supply chains, build high-technology manufacturing, reduce import dependence, and prepare for a world where alliances matter but self-reliance matters even more. This policy research article examines how geopolitical tensions, wars, national security priorities, and the emerging multipolar world order are reshaping defence industries and government defence policies across major nations. Why Defence Spending is Rising Globally The first reason is the return of conventional war. The Russia–Ukraine war demonstrated that modern warfare can consume ammunition, missiles, drones, air defence systems, and armoured platforms at a pace much faster than peacetime defence industries […]