ABSTRACT
This Special Section examines how Western allies and partners across the Euro-Atlantic and Indo-Pacific regions are developing new ‘modes’ and ‘modalities’ of security cooperation to strengthen their ties in the face of intensifying strategic competition. Institutional ‘modes’ of security cooperation are evolving in innovative ways, exemplified by new platforms for cross-regional collaboration, such as the NATO-IP4, and the rise of minilateral initiatives like AUKUS, GCAP, and potentially the Quad (Plus). Simultaneously, the functional ‘modalities’ of security cooperation being adapted to meet the demands of strategic competition, with practical activities ranging from multi-domain combined exercises to unprecedented joint techno-industrial projects. The series of analyses in this Special Section explore these interlocking and overlapping trends in contemporary security cooperation, offering a policy-oriented perspective on how cross-regional collaboration among allies is evolving both institutionally and operationally.
KEYWORDS:
- Indo-Pacific
- security cooperation
- Euro-Atlantic
- alliance management
- NATO
- AUKUS
Confronting the challenges of strategic competition
A key part of the Biden administration’s foreign policy legacy is encapsulated in its efforts to bolster alliances and partnerships in ways that are both innovative and far-reaching. In a transformed and increasingly perilous global security environment, Washington’s strategic vision was not merely focused on strengthening bilateral and regional ties but has emphasised building bridges across the European and Indo-Pacific theatres. This vision also comports with increased European efforts to more deeply engage with regional partners in the Indo-Pacific region (Abbondanza and Wilkins Citation2024). These efforts have brought about what we might describe as new ‘modes’ and ‘modalities’ of security cooperation—mechanisms designed to foster resilience, interoperability, and collective strength within and between disparate theatres.
This vision is rooted in the recognition that strategic competition has intensified across multiple fronts (Mazarr, Crane, and Frederick Citation2022). In both the Euro-Atlantic and Indo-Pacific regions, there is now broad consensus among Western allies and partners that enhanced security cooperation is no longer a matter of preference but a pressing necessity. With the ongoing war in Ukraine and escalating tensions around flashpoints in the Indo-Pacific, including the Taiwan Strait, South China Sea, and the Korean Peninsula, the United States and its allies face formidable challenges to their security and to the maintenance of the rules-based international order.
These challenges, however, are not confined to individual regions. Increasingly, strategic documents from allied states underscore the interdependence of cross-regional security dynamics (Australian Government Citation2023, Citation2024; Government of Japan Citation2022; NATO Citation2022; Republic of Korea Citation2023). The battlefield in Ukraine already reflects this interconnectedness, with the presence of North Korean personnel fighting alongside Russian forces, while US allies in the Indo-Pacific provide critical material and political support for Kyiv’s war effort (Grgić Citation2025a). This growing awareness of cross-regional interdependence has, in turn, shaped new approaches to cooperation and coordination.
Compounding these challenges is the problem of ‘strategic simultaneity’—the prospect of concurrent or consecutive crises in both regions that could severely strain the collective response capacity of Western allies (NATO Citation2020). Garlauskas of the Atlantic Council aptly warns, ‘Simultaneous conflicts impose challenges so severe that the risk should still be considered high, even if the probability of these two conflicts occurring simultaneously is uncertain’ (Garlauskas Citation2023, n/p). At the same time, the Western alliance grapples with deteriorating military-industrial capacities, while competitors increasingly excel in advanced, game-changing technologies.
In this context, the need for innovation in security cooperation has become imperative. Western allies are being compelled to reinvigorate their national defence strategies while simultaneously developing creative, cross-regional approaches to pooling resources and coordinating efforts. The emergence of new modes and modalities of security cooperation—ranging from shared frameworks for defence technology collaboration to integrated approaches for addressing hybrid threats—reflects this urgent need (Grgić Citation2025b). The Biden administration’s commitment to ‘connecting our partners and strategies across regions’ and forging ‘the strongest possible coalitions to advance and defend a world that is free, open, prosperous, and secure’ is emblematic of this shift in strategic mindset (U.S. Government Citation2022, 16).
As we look to the future, questions inevitably arise about the sustainability of these new modes and modalities of cooperation under the second Trump administration. The first Trump presidency was marked by a transactional approach to alliances and a degree of scepticism toward multilateral commitments, raising concerns about whether the innovative and bridge-building efforts initiated under the Biden administration will endure. Will Washington continue to lead in fostering cross-regional security cooperation, or might shifting priorities and a more inward-focused strategy erode the progress made in forging these new coalitions? These uncertainties underscore the fragility of such frameworks and the importance of institutionalising these efforts to ensure their longevity, regardless of political leadership.
This Special Section seeks to explore the contours of these new modes and modalities, analysing their implications for cross-regional security cooperation in an era of profound geopolitical change. By bringing together a range of diverse perspectives, we aim to shed light on how these innovative approaches are shaping the future of international security and alliance politics.
The modes and modalities of security cooperation
The concept and practice of ‘security cooperation’ is central to US policy and its interaction with its allies and partners but continues to exhibit a (frustrating) protean quality. Before introducing the latest policy developments in cross-regional allied security cooperation, which are covered in depth in the following individual commentaries, it is incumbent to specify what we understand by the term. In essence, security cooperation entails collaboration between one or more states/organisations aimed at achieving enhanced security outcomes. This might appear self-evident, but it also ensures the term is highly elastic (as indicated below).
Notably, ‘security cooperation’ is also interpreted through differing frames by the academic and policy/practitioner communities, suggesting something of a problematic ‘disconnect’. The main cleavage entails divergent attention and interests towards the modes and modalities of security cooperation. Put prosaically —modes are focused on determining ‘what is to be done’, whilst ‘modalities’ are about ‘how to get it done’. Generally speaking, the scholarly community tends toward an emphasis on ‘modes’ of security cooperation, whilst the practitioner community is more concerned with the ‘modalities’ through which cooperative security initiatives are implemented. This is not to say that scholars completely neglect the latter, with directed studies of more granular activities such as arms transfers, joint or multilateral military exercises and training, intelligence sharing agreements and so forth appearing in academic literature, but with these are of a more compartmentalised nature. Hence the distinction—‘academic/modes’ versus ‘practitioner/modalities’—whilst not definitive —appears indicative of divergent interpretations. Channelling the famous military aphorism—‘amateurs talk strategy, professionals talk logistics’—we might say: ‘policy-makers talk modes, practitioners talk modalities’. This section therefore reflects these divergences in a modest contribution to ‘bridging the gap’ between the two respective constituencies, as well as telegraphing its potential analytical utility (George Citation1993).
Modes of security cooperation
From a scholarly perspective, the notion of ‘security cooperation’ could theoretically include a veritable galaxy of instruments, from arms control regimes to collective security, to conflict resolution, and spans realist, liberal-institutionalist and constructivist theoretical traditions (Müller Citation2013). To the best of the authors’ knowledge, there is no precise or satisfactory definition of the term presently available in the IR lexicon. Thus, when it comes to substantive policy focus under the rubric of ‘security cooperation’, the majority of the literature tends to appertain to the institutional ‘modes’ through which strategic policy or defence collaboration is governed. Thus, scholars tend to focus on ‘macro-level’ organisations or other institutional frameworks, such as formal alliances, strategic partnerships, and security-orientated ‘minilaterals’ that provide the political direction of security cooperation (Panda and Ohn Citation2024).
These differing institutional forms of ‘security architecture’ are typically approached as international political entities to be theorised or analysed from a variety of perspectives, whether they be dialogical communication forums (e.g. ASEAN/ASEAN-plus), or practically-driven security instruments, like military alliances (Tow and Taylor Citation2010). Thus, ‘modes’ of security cooperation, as employed throughout the following discussions are understood as functioning institutional relationships with material capacity, though their arrangements differ according to the nature of their compositional framework—a treaty alliance, (bilateral) strategic partnership, minilateral formation, or other (multilateral) security dialogue-based forum (Wilkins Citation2019).
Modalities of security cooperation
In the second instance, for government organisations, ‘security cooperation’ holds a very distinct—if still quite broad—meaning. The US Department of Defense (DOD) contains a dedicated Defense Security Cooperation Agency (DSCA) with a variety of institutional organs aimed at implementing relevant collaborative activities with allies and partners (Defense Security Cooperation Agency Citation2025a, Citation2025b). The definition provided is as follows:
Security cooperation (SC) comprises all activities undertaken by the DoD to encourage and enable international partners to work with the United States to achieve strategic objectives. It includes all DoD interactions with foreign defense and security establishments, including all DoD-administered security assistance (SA) programs, that build defense and security relationships; promote specific U.S. security interests, including all international armaments cooperation activities and SI [Security Assistance] activities; develop allied and friendly military capabilities for self-defense and multinational operations; and provide U.S. forces with peacetime and contingency access to host nations (Defense Security Cooperation Agency 2025, n/p).
This indicates that while the overarching ‘modes’ of security cooperation above represent the institutional defence and security relationships and frameworks that provide political direction/mandate, at the ‘micro-level’ of practical implementation by government agencies, the focus is on the ‘modalities’ (i.e. actual ‘activities’ above). Together, practitioners are focussed on the mechanics of implementing politically determined initiatives through the appropriate modalities so it can take effect—i.e. ‘making it work’. That is, at this level, practitioners are concerned with performance outcomes, rather than political/strategic decision making.
Of course, these two levels, political and practical, are co-dependant and interactive since one cannot achieve tangible security cooperation without both these elements, something that will be visible throughout the commentaries in this Special Section. Indeed, one of the challenges identified by practitioner experts is how security cooperation under a particular institutional mode translates its decisions into the appropriate modalities for actionable results (Conversations with DCSA personnel, Citation2024). Ensuring optimal interface between what are often quite distinct—even ‘siloed’—policy making, and bureaucratic implementation organs is also a key challenge. This is especially the case for the newly-founded institutions considered in this Special Section as they come to grips with setting agreed parameters and processes to achieve objectives, and concomitantly encounter pre-existing bureaucratic obstacles, which will require deft navigation. From both vantagepoints the topic of security cooperation is one of near infinite complexity (and perilously subject to ‘concept creep’). In the short space of this Special Section we cannot probe its dimensions to their full extent—which requires a more protracted research agenda—but have rather concentrated on making it tolerably digestible to the readership.
Cross-Regional networking
The deteriorating global security environment has given rise to newly-crafted institutional modes of security cooperation, and the modalities required to realise their objectives are being tailored accordingly to prosecute multi-dimensional strategic competition. This Special Section focuses on new developments in cross-regional security cooperation between allies and partners both within and across the Euro-Atlantic and Indo-Pacific regions.
At the outset it is important to situate the newer developments featured in this Special Section within the larger context of how US alliance structures (modes) are being transformed to augment security cooperation with allies and partners (Wilkins Citation2023). Appreciations of US allied relations have typically segregated its multilateral alliance framework in Europe (NATO) and its set of separate bilateral alliances in Asia (the ‘hub-and-spokes’) into different models. Simón, Lanoszka, and Meijer (Citation2021, 361) argue that such thinking is now ‘obsolete’, and that that traditional dual ‘multilateral/Europe’ and ‘bilateral/Asia’ alliance structures have been independently transformed into ‘nodal defence’ systems. They each represent ‘a cumulative intertwining of bilateral, minilateral and multilateral initiatives’—that is multiple ‘modes’ of security cooperation within each region (Simón, Lanoszka, and Meijer Citation2021, ibid).
But, in line with the NSS directives quoted above, this ‘nodal’ model is now converging more concretely in a cross-regional context in light of two major developments. First, and most strikingly, at the ‘macro-level’ a new multilateral platform for cross-regional security cooperation appeared in 2024, the NATO-IP4, explicitly connecting the two separate alliance structures together at the highest level. This new institutional mode of security cooperation encompasses all 28 NATO member states, plus ‘Major non-NATO allies ’—Australia, Japan, South Korea and New Zealand (the ‘hub-and-spokes’ allies—though the Philippines and Thailand are not presently directly included). This development creates a specific cross-regional forum that can potentially formulate strategic objectives and pursue outcomes across the two regional alliance systems. Importantly, this tallies with, and is amplified in line with both EU Indo-Pacific strategy documents, and those of individual European powers such as the UK, France, Germany, the Netherlands and Italy, that seek to build and deepen additional cross-regional connectivity with Asian partners (British Government Citation2023; Dutch Government Citation2020; European Commission Citation2021; French Government Citation2022; German Government Citation2020; Italian Ministry of Foreign Affairs Citation2022).
Additionally, lower-level modes of security cooperation are advancing across multiple lines of effort between select European and Indo-Pacific members of the NATO-IP4 within bespoke cross-regional minilateral formats. Bilateral arrangements notwithstanding, the locus of action for practical implementation (modalities) at the ‘micro-level’ is often to be found within minilateral institutions such as AUKUS and the Japan-UK-Italy Global Combat Aircraft Programme (GCAP). These minilaterals are indicative of practical cooperation that serves the higher objectives the Western allies. These minilaterals are often anchored in prior (bilateral) Strategic Partnerships—non-alliance commitments to security cooperation—from both Europe and the Indo-Pacific and generate the necessary modalities to implement defence-industrial, advanced technological, or other forms of military integration, and are thus exemplary of what cross-regional security cooperation is designed to achieve (Wilkins Citation2008). As a result, these Euro-Asian minilaterals within the ‘nodal’ structure now bind states across the two regions, rather than (mainly) within them.
Thus, where the antecedent nodal model identified above concentrated on evolving alliance structures around various modes of cooperation, and the functional roles that allies played in the overall ‘networked alliance architecture’, these new developments point to the emergence of tangible cross-regional security cooperation through new modes and modalities. From this perspective, the nodal structure becomes akin to a cross-regional ‘meta-alliance complex’ superintending a matrix of modes and modalities of security cooperation. The components of what Former US National Security Advisor Jake Sullivan described as a ‘latticework’ of connections work along synergistic lines of effort towards common Euro/Indo-Pacific strategic objectives to create force-multiplying outcomes for the US and its allies in both theatres (Council on Foreign Relations Citation2021, n/p).
Special section outline
The Special Section contains five commentaries pertinent to security cooperation across regions and across multiple modes and modalities. The first two explore the trend of cross-regional security cooperation to analyse the creation of the NATO-IP4 as a new institutional mode explicitly designed to coordinate allied strategic policy.
Grgić’s analysis focuses on the United States’ efforts to promote cross-regional security cooperation between the Euro-Atlantic and Indo-Pacific theatres. It argues that the Biden administration’s policy entrepreneurship played a critical role in fostering these linkages, as reflected in initiatives such as NATO-IP4 and AUKUS. The analysis assesses the legacy of US cross-regional engagement and the challenges ahead in institutionalising and maintaining these partnerships amid shifting political dynamics. It argues that the long-term sustainability of these efforts remains uncertain at best under the second Trump administration.
Moore provides further justification for the cross-regional approach, arguing that NATO has an opportunity not only to enhance political dialogue and practical cooperation with the IP4, but to enlist these partners in sustaining the liberal, rules-based international order. She argues that situating NATO's approach to these partners in the context of a larger, more forward-looking partnership strategy would highlight a values-based community that bridges North America, Europe, and the Indo-Pacific. Such an approach would also strengthen NATO as a political platform for discussion of a broad range of issues that in an increasingly seamless strategic environment concern the Allies and partners from around the globe.
The second half of the collection supplements and extends the initial NATO-IP4 focus to elaborate upon the adaptations in modes and modalities of cross-regional security cooperation by looking at how practical cooperation is realised through various minilateral formats, including AUKUS, GCAP and, prospectively: the Quad, and how these work towards the greater benefit of the overall NATO-IP4 membership. It further emphasises combined military operations as one of the salient modalities through which security cooperation is practically operationalised.
Wilkins approaches the issue of cross-regional security cooperation from the vantage point of coalition-building. With US policy documents, such as the 2022 NSS and Indo-Pacific Strategy, adamant on the need to forge enhanced or new coalitions of allies and partners, his analysis explores how this is being achieved, or could be prospectively achieved, including in a cross-regional context. It highlights the challenges and opportunities for enhancing connectivity between existing (largely Indo-Pacific-orientated) minilateral formations, and how these may culminate in a ‘network’ of cross-institutional and cross-regional linkages. This analysis sets the stage for expansion beyond the NATO-IP4 frame of reference to encompasses other modes and modalities of security cooperation being pursued.
Heng’s analysis addresses the question of modalities by examining how combined military exercises have manifested in various institutional modes—bilateral, minilateral and multilateral —further reinforcing the ‘latticework’ approach to cross-regional cooperation. Assuaging a partner’s security anxieties through tailored exercise scenarios and managing politico-strategic nuances, Heng contends, is an essential first step. Examining critical enablers such as logistical and legal frameworks, he then demonstrates how cross-regional exercises have evolved to become more regular and operationally complex. Through Heng’s analysis, the practicalities and actual substance of cross-regional security cooperation becomes more apparent.
Cannon examines how the Quad serves as an informal yet pivotal mechanism for shaping cross-regional security cooperation. He argues that its adaptability allows it to address shared threats and challenges while preserving members’ strategic autonomy, making it a model for initiatives like AUKUS and NATO-IP4. However, its relevance shifts with members’ threat perceptions. Highlighting Japan’s role in shaping the Quad’s vision, Cannon demonstrates how middle powers can lead cross-regional cooperation. Despite coordination challenges, the Quad’s diverse modalities, such as technology and maritime security initiatives, show how issue-based cooperation drives strategic realignments. Ultimately, he contends that the Quad has fostered a bottom-up nodal security framework, reinforcing cross-regional security against authoritarian influence.
Summary
This collection of commentaries explores and analyses some of the most significant developments in allied security cooperation within the cross-regional context of the Euro-Atlantic and Indo-Pacific. Its aim is to provide analytical coherence to a diverse and fragmented set of policy initiatives. However, the continuation of the current trend toward strengthening both the modes and modalities of cooperation is by no means guaranteed. Numerous political and bureaucratic obstacles must be overcome to optimise the benefits of cross-regional collaboration, as the analyses in this collection vividly illustrate.
Moreover, shifting environmental and domestic factors have the potential to either accelerate or impede cross-regional security integration—not least the policies of the new US administration under President Trump. Given Trump’s well-documented scepticism toward NATO and alliances more broadly, it is possible that cross-regional cooperation led by Washington has already reached its high-water mark. Nonetheless, with a range of European and Indo-Pacific stakeholders actively invested in the process for their own purposes, as evidenced in their respective Indo-Pacific strategies, some degree of cross-regional security cooperation is likely to persist in various forms. In the interim, policymakers and practitioners will continue seeking workable solutions to align collective politico-strategic objectives with practical modalities for effective cooperation.
Acknowledgements
The participating authors of this Special Section would like to acknowledge the kind support of the Defense Security Cooperation University (DCSU) for the opportunity to present papers upon which these analyses are based at the Third annual Security Cooperation Conference, Washington DC (Oct 28-30, 2024).
Disclosure statement
No potential conflict of interest was reported by the author(s).
