The Regional Security Monitor is an annual analytical report that tracks and explains security dynamics across global regions, using the Regional Security Complex Theory as conceptualised by Barry Buzan and Ole Wæver in their book “Regions and Powers: The Structure of International Security.” It offers concise, research-based insights into how threats, actors, and power relations interact within and across regions, revealing both current events and deeper structural patterns shaping regional and international security.
Regional Security Complexes – Multiregional 2024-2025
by Aleksandra Vušurović
Introduction
In recent years, the ongoing debate on the broader implications of the unipolar moment decline for the international system has hardly yielded consensus so far, and the current order has been referred to as simultaneously showing “elements of unipolarity, bipolarity, multipolarity, and nonpolarity” (Munich Security Conference, 2025). In 2024-2025, the inter-regional security logic has been largely navigating this complexity and transition to the unknown with the accelerating diffusion of power, shared Global South drive for multipolarity and the crisis of the liberal democratic order that has profoundly challenged the foundations of the post–Cold War system. International ideological bifurcation and sharp societal polarizations are on the rise and being increasingly exploited by domestic and external actors for destabilization in the complex and highly politicized security environments, like that of Europe or the United States. Despite the rise of environmental, human and transnational threats affecting the interconnected global security landscape today, these dynamics are indivisible from the broader regional patterns of security shaped by historical legacies, mutual interdependencies, and ongoing securitization and desecuritization processes.
The Regional Security Complex Theory (RSCT) has long been one of the most comprehensive frameworks for studying regional security dynamics, yet it has also faced calls for update and revision to reflect the evolution of the international security landscape over the past two decades, as well as to account more for the processual and relational nature of regional interdependencies. This article seeks to apply and test the RSCT framework in the analysis of inter-regional security dynamics that have been most transformative and profoundly encompassing in capturing the ongoing flux of the international security order over the last two years.
Revisiting the RSCT
Regional Security Complex Theory (RSCT), developed by Barry Buzan and Ole Wæver (2003) and rooted in both neorealist and constructivist thought, emerged from the recognition that understanding the post-Cold War security environment requires renewed attention to the territoriality and regional dimension of security. According to RSCT, it is within the regional clusters, or regional security complexes (RSCs), that the security interactions occur with most intensity and through the interdependent patterns of securitisation and desecuritization processes in various sectors, while three other levels of analysis (domestic, inter-regional, and global) complement its comprehensive analytical framework.
While RSCT has been criticised for the relatively static nature of some of its neorealist assumptions (Jarząbek, 2019), it has also faced limitations in identifying and interpreting structural change in the balance of power across multiple levels of analysis and integrating the multiregional perspective. In the wider historical context inherent to the framework, Buzan and Wæver trace the evolution of regional security through the emergence of enduring RSCs within the global system dominated by great powers, rather than through their inter-regional dynamics, which at the time of the theory’s formulation remain mainly reduced to penetration by great powers and sporadic spillovers between adjacent RSCs. Two decades since the theory’s development, the contemporary global security landscape being redefined by the erosion of US-dominated unipolarity, wider diffusion of power across global and regional actors, proliferation of transnational threats, intensified cross-regional (de)securitizations and overall more porous boundaries between RSCs, calls for the expansion of RSCT framework to account for a more nuanced and diffused global security dynamics encompassing complex and simultaneous interactions between multiple RSCs. The brief overview and analysis of the key inter-regional developments in 2024 and 2025 presented below will attempt to test the relevance and explanatory power of RSCT in regard to the emerging phenomena of the new geopolitical age.
Inter-Regional Security Dynamics in 2024–2025
The dynamics of interaction between the European and the post-Soviet RSC centred on Russia is arguably one of the most intense and consequential inter-regional relationships in the world today. Since the 2014 annexation of Crimea and especially after 2022, their frontier (Jarząbek, 2019) became a war zone, and the two complexes started to fuse into a single conflict system with opposing poles. The protracted war and geopolitical instability have impeded the European Union’s longstanding attempt to uphold its identity as a normative and civilian power reliant on US protection. The military crisis, along with the unprecedented internal and external contestation of the liberal international order embodied by the EU, shifted the European securitization logic towards collective defence and integration (e.g., through SAFE instrument and Readiness 2030 agenda), energy security, democracy and hybrid resilience (ProtectEU strategy) to confront Russia’s increasingly expansive war objectives, underpinned by its securitization of Western domination and the pursuit of dominance in its near abroad (European Commission, 2025; 2025).
In 2025, Europe remains deeply affected by other inter-regional vulnerabilities, including the growing securitisation of economic relations following Donald Trump’s trade wars and energy dependencies linked to Middle Eastern instability (Aurora Energy Research, 2025). With the continuing war in Ukraine, central to deepening the European security crisis is the faltering US security commitment to Europe and increasing securitisation of the transatlantic relationship, which remains foundational for both European RSC security architecture and global deterrence. The divergent US and EU priorities regarding NATO cooperation in response to the Ukraine war and the burden-shifting of European security from US to Europe (Bergmann, 2025) as well as the core internal EU divisions over US unconditional military support to Israel, adherence to international law and responses to the war and humanitarian crisis in Gaza (Soler i Lecha, 2024) have had an unsettling effect and put sustained pressure on the alliance. With the intensifying great-power competition and closer Sino-Russian security alignment, Europe has been seeking to strengthen its defence-industrial cooperation with Canada through the EU–Canada Security and Defence Partnership (EEAS, 2025) and Indo-Pacific democracies through the EU Indo-Pacific Strategy (Grangier, 2025), aiming to project strategic influence in the region and secure supply chains, technology, and critical maritime logistics (Schreer, 2025).
The North American RSC is the world’s first modern security community centred around the sole global superpower that has been penetrating nearly all other complexes under the grand strategy of liberal internationalism, while remaining largely desecuritized internally. In 2025, the United States under the second Trump administration made a decisive policy turn that signalled the world a divergent path. Its new and occasionally intimidating securitization agenda towards the US regional and transatlantic allies, announced intentions for disengagement from overseas security commitments like the Baltic Security Initiative or moving toward “transactional retrenchment” in security assistance programs to Europe (Robertson, 2025; Čopič, 2025), the freeze of the world’s largest foreign aid agency and weakening of multilateral norms through multiple withdrawals opened the way for diverse global actors to step up (Munich Security Conference, 2025). On the domestic level, the United States face new forms of destabilisation with far-reaching implications on regional and global levels. Fuelled by further polarization under multiple ideological and societal fault lines, including the enforcement of anti-immigration policies by mass arrests, deportations and violent raids by federal ICE officers, the increasing political violence and authoritarianism have been deepened by the unprecedented criminalisation of Antifa as a domestic terrorist organisation based on a left-wing conspiracy following the assassination of the conservative activist Charlie Kirk (Patel, 2025).
The evolution of the China-centred tripolar Asian supercomplex is inextricably linked to the Indo-Pacific becoming the forefront arena of the great-power rivalry in the 21st century. Amalgamated from the merger of East Asian and South Asian complexes, it has been solidified by China’s increasingly assertive strategic posture, military buildup including a 13-fold increase in military spending over the last 30 years with China’s actual defence spending in 2025 being estimated to $318-471 billion (Funaiole & Hart, 2025), as well as the intensified regional security dynamics in the wider Indo-Pacific linked to the growing footprint of the Belt and Road Initiative and the emergence of new key security actors like Australia. Although facing domestic challenges, India stays committed to its great power aspirations and to its policy of multi-alignment as a way of dealing with China’s strategic influence and growing presence in India’s maritime domain (Sukaedi & Yogaswara, 2024), while Japan’s response to growing geopolitical concerns is more focused on strengthening defence capabilities and multi-regional security dialogue through the Free and Open Indo-Pacific (FOIP) strategy and intensified EU security cooperation (Munich Security Conference, 2025).
Despite the sub-regional conflict formations in South Asia (including India and Pakistan, with Afghanistan being increasingly involved) and Northeast Asia (the Korean peninsula, Taiwan and China) within the predominant security regime, an all-Asian conflict formation involving its nuclear powers is unlikely. While the United States is strengthening its position in the region through initiatives like the Quad and AUKUS, the future regional dynamics will be determined by the interplay in the growing rivalry between the US and China, with Taiwan remaining a critical red line where a military escalation would trigger a global economic disruption far exceeding the scale of the shock caused by the Russian invasion of Ukraine in 2022 (Masuda & Mattelaer, 2024). The increasing, although asymmetric, Sino-Russian strategic and economic cooperation has drawn particular attention (Kapoor, 2024), and is part of the evolving patterns of China’s inter-regional penetration, along with its salient presence in Africa, the Middle East, South America, as well as the Western Balkans and Central Asian sub-complexes.
The RSCT-informed analysis of key inter-regional developments in 2024-2025 has several theoretical implications. Firstly, the emergence of major conflict territorialised in Ukraine proves some of the key assumptions of RSCT regarding the prevalence of most intensive security interactions in physically adjacent areas and persistence of historical patterns of amity and enmity, like those originating from Cold War legacies. Secondly, and in line with RSCT framing, the contested role of Ukraine in the unfinished division between the European and the post-Soviet regions eventually became object of Russia’s great power securitization in pursuit of regional dominance, while the role of Afghanistan as an insulator between the three RSCs persisted even after the Taliban takeover in 2021 and its growing destabilizing effects for India and Pakistan (Raja & Rani, 2025). The same stands for Turkey and its unique hybrid position of both insulator and penetrator with increased influence in high-stakes global affairs (Barrinha, 2014). On the other hand, multiple crisis of European security and its interconnectedness with broader social and political trends is clearly the result of transnational dynamics – including the spike in hybrid and cyber threats aided by Russia’s disruptive technologies (Shamrai, 2023), securitization of migration flows and other forms of weaponised interdependence, involvement of overseas states in Russia-Ukraine war (Iran, North Korea, China) and their mutual alignment, which makes it more difficult to uphold the principle of regionality and apply RSCT effectively. The multiregional conflictual dynamics have elevated the concept of energy security to the forefront of strategic concerns in the Middle East, Europe, Asia and beyond, and the cross-regional securitisation of energy flows has been carving new patterns into security interdependencies, like the EU-Turkey-Russia energy triangle (Fırat, 2024).
A few scholarly attempts to bridge state-centric aspects of the RSCT framework have done so by employing the concept of macrosecuritization (Buzan & Wæver, 2009; Jarząbek, 2019). Applied to the wider Indo-Pacific, it is seen as a “macrosecuritized constellation” rather than region, where the referent object is the rules-based international order macrosecuritized by a group of actors like Japan, Australia, India, the US and others, as being existentially threatened by China’s rise (Smith & Bacon, 2025). The emergence of the hybrid Arctic RSC is another example of multisectoral securitization (environmental, military, economic, societal) and fierce regional competition of adjacent NATO states, Russia and China in a power struggle that overlaps with the spatial boundaries proposed by RSCT (Østhagen, 2021, Koutsenko, N.D.). The rising role of non-state actors and international institutions that defy the essential RSCT idea of territoriality is another emerging phenomenon that poses major challenges for RSCT application. Although without a formal security role for its members, BRICS as the most influential intergovernmental organization of non-Western states accounting for nearly half of the world’s population, has been increasingly promoting the alternative multipolar world order and counter-narrative to Western domination through strengthening geopolitical resilience of its members, particularly through security discourse in the economic and financial fields, as highlighted at the summit held in 2024 in Kazan, Russia (Council of Councils, 2024).
Apart from existing limitations for adequately accounting for some of the changes in the contemporary security environment, the RSCT provided a realistic future outlook for the global level polarity dynamics back in 2003. Their forward-looking inquiry remains particularly relevant today. It underscores the crucial role of the US internal developments, such as the unwillingness of its citizens to carry the burden of its international role, the possible decrease of state security legitimacy and increased focus on internally constructed threats, in affecting the US global commitment (Buzan & Wæver, 2003) and potentially shifting its policy from unilateralism toward isolationism. Complemented with unprecedented challenges to the international order posed in this century by Russia (although not limited to it), the assertive strategic posture of China in its quest to disrupt Western dominance, and diverse multipolarising vectors of a growing number of Global South powers, the outlook for the future in 2025 has to accommodate various, divergent, and largely conflicting visions of the world.
Conclusion
Over the last two years, profound transformations of the global order have proved some of the core assumptions of RSCT but also brought new phenomena, like deterritorialised threats and increased role of international organisations, to the forefront of the regional and global security agenda. Crises and complexity accompanying the global order in its evolving flux have been particularly transformative in the inter-regional relations and security systems of Europe and post-Soviet space centred on Russia, Asia and the wider Indo-Pacific, and North America as the epicentre of the changing global power balance and the intensifying strategic rivalry between the United States and China. Behind great power competition and (multi)polarisation trends, the global environmental concerns and climate change dominate the landscape of shared threats posed to the global and regional interdependence.
In the European˗post-Soviet frontier, the European penetration into Ukraine through its EU member candidacy, military aid and NATO coordination has effectively drawn the country into the European RSC, while the development of militarized security interdependence between these two complexes and Russia’s intensified hybrid war and grey-zone exploitation (including UAV and jet incursions) may be seen as a formation of the larger European supercomplex under conflictual Hobbesian terms and pervasive patterns of enmity. However, the extent to which economically weakened Russia, facing imperial overstretch and bordering China, may sustain its geopolitical position of a global actor in the future remains debatable.
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