Rethinking Security in the Twenty-First Century

Lucrezia Brunelli 

Introduction

The concept of security has frequently been discussed in the context of international relations, strategic studies, and broader political and social debates, yet it has often been employed without sufficient conceptual precision. As Arnold Wolfers (1952) notoriously observed, security is an “ambiguous symbol”, a flexible term without a precise meaning and whose interpretation depends on the actors and contexts involved. Since Wolfers’ contribution, scholars have tried to refine and broaden this concept. Richard Ullman (1983), for instance, moved away from the narrow traditional definitions mainly concerned with military threats, proposing instead a notion of security focused on non-military dangers capable of undermining a state’s stability and well-being. Barry Buzan (1991) further developed this approach by conceptualising security as a multidimensional phenomenon, extending across military, political, economic, societal, and environmental sectors. Despite these efforts, relatively little scholarly attention has been devoted to analysing what “security” actually means, as David Baldwin (1997) noted in his essay “The Concept of Security”: different schools of thought have attempted to address this question, but they have been more concerned with redefining the policy agendas of nation-states, rather than with the concept of security itself, which has often been neglected and taken for granted.

The deep transformations of the global scenario have brought back discussions on the concept of security. The development of new technologies, the appearance of new actors and the intensification of non-traditional threats, such ascyberattacks and natural disasters, has reshaped the way states perceive and approach national security in 2025. Today,states face multiple security risks and operate in a complex environment, which requires them to address both traditional territorial concerns and non-military transnational challenges. The fundamental questions that Baldwin attempted to answer in his essay (1997) have come back into focus: What should a state protect? From what threats? By what means?

This new context brings us to consider whether the contemporary challenges have changed the very concept of security or if we simply specify it differently. Are broader theoretical frameworks required, or do the classical definitions provided by Wolfers, Ullman and Baldwin still apply today? In order to properly answer these questions, we should acquire a deeperunderstanding of the security landscape in the 21st century.

In what follows, I will present three different sections. First, I will analyse the transformation of the global security environment and its implications for states’ defence strategies. Second, I will examine the new dimensions and priorities of security, with particular attention to emerging domains, such as cyber, economic and environmental security. Finally, Iwill explore the new instruments and resources available to states for developing their national security policies. The purpose of the essay is to assess whether the contemporary changes imply a redefinition of the very concept of security or a mere reconfiguration of its specifications.

1. The Transformation of the Security Environment

Since the Cold War era, the contemporary security environment has drastically changed. Security was primarily understood in military and territorial terms and discussions about it revolved around the balance of power between the United States and the Soviet Union. The dominant assumption was that states were the primary objects and providers of security, and that threats mainly derived from other states. Today, this paradigm has evolved: the bipolar and largely state-centred understanding of threats that characterized the Cold War has been replaced by a multipolar view. This has given rise to a more fluid, interconnected and unpredictable world, where threats are increasingly hybrid and borderless.

As Richard Ullman (1983) argued in his essay “Redefining Security”, threats to national defense cannot be reduced to the military dimension, as they extend far beyond it to include any event that could quickly and drastically undermine a state’s capacity to preserve its internal stability and the well-being of its citizens. This reasoning has regained relevance, since the sources of insecurity in 2025 have diversified and expanded. States’ security agendas now include manydifferent issues that range from cyber warfare and disinformation campaigns to pandemics, natural disasters and climate change.

Recent international events are clear examples of the hybrid nature of contemporary security threats. The Russo-Ukrainian conflict, for instance, has reshaped our conception of warfare: while traditional military concerns have come back to the center of security debates, it has also produced new defense challenges, in particular disinformation campaigns and cyberattacks perpetrated by Moscow to undermine the Ukrainian institutional apparatus. 

Additionally, the spread of the so-called “AI-generated deepfakes”, such as videos disseminating misleading informationto advance political aims, has become a global security concern, because they erode citizens’ trust in information and democratic institutions. Even the interdependence of national economies poses serious threats to security: the COVID-19 pandemic, for example, has exposed how vulnerable global supply chains are and how this has repercussions on states’ stability. At the same time, the always more frequent climate catastrophes, from floods to wildfires and droughts, have made the environmental decline a direct security concern. 

Together, all these examples reveal how security is not limited to the military sphere, but rather has diversified origins that cross sectors and borders.

The picture is further complicated by the wide range of actors operating in the international arena. The 21st century has witnessed the rise of new players capable of influencing, and also threatening, national and global security. The state remains the primary actor responsible for providing security, but there are also many non-state actors playing important roles, in particular international organizations (e.g., UN; EU), military alliances (e.g., NATO), academia, NGOs, the civil society, and the private sector. Today, crucial digital systems are under the control of big private tech companies that retain sensitive information about citizens. A leak of such information may represent a national security problem. At the same time, non-state actors, in particular terrorist groups, threaten to disrupt societies worldwide. One of the most recent examples was the terrorist attack in Manchester in October of this year: two citizens were killed outside a synagogue and many others were seriously injured (McArthur, 2025). Terrorist attacks directly affect national safety, as they cause a widespread sense of fear and insecurity, generate unrest, and undermine public trust in the government and its institutions.

Finally, it is crucial to address the transnational nature of security threats in 2025: crises that once remained confined tonational borders, now propagate rapidly around the world. Threats that appear to be national in scale, actually cut across borders, becoming global problems requiring global solutions. As a result of this growing international interdependence, domestic and global security are inseparable, they cannot be detached from one another. Therefore, no state can ensure its own safety without taking into account the vulnerabilities of others. 

In light of this, the concept of security must be reconsidered within the new contemporary context, but this does not necessarily imply its redefinition. Rather, we need to acknowledge that the conditions under which security is pursuedhave changed and have become much more complex and intertwined.

2. New Dimensions and Priorities of National Security

The transformation of the global environment has reconfigured the list of national security priorities. In 2025, states’ defense cannot be limited to military concerns: the picture needs to be expanded, adopting a comprehensive approach that combines traditional threats and non-conventional challenges. The way states and societies define and pursue security today is shaped by the interaction of military, digital, economic and environmental dimensions.

The military sphere remains the most traditional and visible expression of national security. Despite the diversification of current threats, the capacity to deter armed attacks and defend the national territory continues to be a core priority of the state. The enduring relevance of military capabilities has been confirmed by different theaters of conflict worldwide, such as the Russo-Ukrainian conflict or the Israel-Gaza war. Nonetheless, in today’s world, the military component alone is not sufficient to ensure national stability. Effective security now depends as much on adaptability and coordination across different sectors and as it does on advanced weaponry and military superiority.

In this context, cybersecurity has emerged as one of the most pressing new dimensions of national defense: technological development and digital innovation have opened a new security frontier, which governments must pay attention to. States are increasingly dependent on digital systems for purposes including communication, transportation and financial transactions. This has exposed them to new risks, seriously affecting their stability. Critical infrastructures, such as public institutions, hospitals or power grids, are now the main targets of cyberattacks, as revealed for example by the ransomware attack on the Colonial Pipeline in the United States. In the spring of 2021, fuel distribution along the US East Coast was temporarily paralyzed and the impact was so devastating that President Biden had to declare the state of emergency (INSURICA, 2024). The hacker attack emphasized the importance to effectively develop cybersecurity branches as a fundamental pillar of the security agenda.

Another essential dimension that needs to be considered is economic security. The state’s economic power plays a crucial role in its stability and well-being, both domestically and on the international plane. In recent decades, globalizing processes have fostered a growing interdependence, which has resulted in highly structured supply chains, reaching every corner of the globe. On the one hand, global supply chains benefit states’ economy, allowing for lower production costs, guaranteeing access to a wider range of resources and increasing efficiency and productivity. On the other hand, however, they are highly vulnerable to disruptions and increase states’ dependence on other countries (GEP, 2025). Therefore, theconcept of “economic sovereignty” has become a key national interest: states want to autonomously determine their own economic strategies and manage their resources without heavy external interference. After Moscow’s invasion of Ukraine, for instance, the European Union has made efforts to reduce its reliance on Russian energy. States are now trying tosecure their control over strategic resources to achieve greater economic resilience and autonomy.

The current view of security also involves the environmental dimension. In his essay “Redefining Security” (1983), Richard Ullman anticipated that the degradation of the environment and the scarcity of natural resources are likely to cause serious security risks. Recently, there have been many instances of environmental catastrophes around the world, including hurricanes in the United States and in the Philippines, record-breaking heatwaves in Japan and Australia, destructive floods in Spain and Brazil, and devastating earthquakes in Taiwan and India (Kogut, 2025). Such natural disasters, often climate-change-related, are now considered top priorities in national and international security agendas, highlighting the link between ecological conditions and human safety. 

Taken together, these new dimensions have changed the way national security is typically understood: the absence of military threats is no longer sufficient. States are required to face and adapt to a wide range of risks, promoting and protecting national objectives across different spheres.

3. The New Instruments and Resources of National Defense

Changes in the global security environment and the broadening of its dimensions have inevitably reshaped the methods through which security is pursued. Investing in the military industry is not the only path available to states to ensure their stability. The nature of current threats, in fact, has led them to develop and integrate new tools and resources, and to adopt strategies that combine conventional defense with digital innovation and multilateral cooperation. 

Among the new security practices, the adoption of hybrid defense strategies is one of the most effective. They combineconventional warfare with non-military instruments, such as cyberattacks and economic sanctions, in order to enhance states’ protection and resilience. This approach has been widely used by NATO member states in response to the Kremlin’s hostile actions in the war against Ukraine. The hybrid attacks perpetrated by Moscow, combining misleading propaganda campaigns, trade tariffs and cyberwarfare, have triggered an equally hybrid reaction from NATO and the EU. Their support to Ukraine has not been limited to providing direct military assistance, but they have also mobilized intelligence agencies, strengthened cyber defense and implemented coordinated economic sanctions, in order to reinforce the Ukrainian defense capacity (Romansh, 2025).  

At the same time, the development of new technologies has had a decisive role in contemporary defense practices. States have gained access to advanced technological tools, in particular, artificial intelligence, big data analytics and quantum computing, which have rapidly transformed the way states operate. They are now able to monitor potential threats, identify and counter hacker intrusions, safeguard territorial borders and protect sensitive digital information (Dylan & Stivang, 2025). Today, technological independence and cyberspace control are the main reasons behind states’ competition to try to preserve their own safety. This shows how technological innovation has had a twofold effect: on the one hand, it has brought about new threats to national security, but on the other it has offered states new opportunities to increase their safety. 

Finally, the transnational nature of contemporary threats has made unilateral responses inadequate and insufficient. Now, security requires cooperative strategies, shared intelligence and common standards. Thanks to alliances, regional integration, and multilateral agreements, also small and medium-sized states, that were once disadvantaged by their limited military capacities, can now achieve relative security. Military spending and warfare capacity remain crucial, but in 2025 security equally depends on multilateral cooperation. The European Union, for example, has designed a series ofcollective defence initiatives in Asia and Africa, in order to improve their capacity to respond to threats and manage internal crises, and to reduce their dependence on the US and NATO. 

Conclusion

The current trends of the international system have deeply transformed the way security is understood and pursued in the 21st century. It has become an even more complex and multidimensional concept: the traditional state-centred military vision has been challenged by the new global dynamics. The rise of cyberattacks, disinformation, economic vulnerabilities and environmental catastrophes has expanded what “security” stands for. States’ protection now impliesnot only border defense, but also the preservation of their digital infrastructures, the strength of their economy, and the sustainability of their environment. Moreover, the dividing line between national and international interests has become blurred, forcing states to act within an interconnected system of cooperation.

These transformations have redefined the security agenda without changing the core concept of “security”. States continue to seek protection from threats to their existence, but their priorities and the methods through which thisprotection is achieved have become more diversified. Traditional military deterrence continues to play a fundamental role, but it now coexists with hybrid defence strategies and technological innovation. In addition to this, multilateralism and alliances now make it possible to expand national defense capabilities. 

It becomes clear that the very essence of security has remained unchanged, although its expressions and specificationshave evolved over time. The fundamental principles provided by Wolfers (1952), Ullman (1983) and Baldwin (1997) remain valid: security continues to refer to states’ effort to protect themselves from threats to established values; military and non-military dangers are equally urgent and deserve the same attention; and the concept of security must be effectively specified to remain analytically useful. What has changed are only the objects of defense and the meansthrough which it is guaranteed.

In conclusion, security now encompasses different dimensions, that span from cybersecurity to economic and environmental protection. The concept itself has not been replaced, but rather reinterpreted and recontextualized; it has adapted to the new circumstances of the current scenario. However, the very essence of security remains what it has always been: the attempt to secure protection and the effort to safeguard what states and societies value the most.