Neorealism: Internal Debates and Relevance to Space Militarisation

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This essay shall explore the concept of neorealism (also referred to as structural realism), exploring its fundamental claims and lines of argument, as well as its points of contention with both classical and other strands of realist theorising. Subsequently, this essay then applies the theoretical contributions of neorealism to the continued militarisation of outer space most notably the contributions of offensive realism in understanding why, despite the enactment of the Outer Space Treaty[1], major powers have continued to develop defensive and offensive capabilities for use against targets in space. Through the use of neorealism theory, this essay will posit the claim that it provides a suitable (though limited) theory, with which to understand why states have continued to militarise one of the most important aspects of the international commons.

Before beginning to outline the neorealist theory, this essay must bring to the fore the point that, as with any reasonably new area of research, investigations into astropolitics (and space security more specifically) remain limited in their prevalence within the field of International Relations. Such limitations are even more noticeable given the level of technical knowledge necessary for understanding space security from an IR perspective.

Neorealism fundamentals

This first section explores the fundamentals of neorealist theory, including its core assumptions, as well as where it coincides with classical realism in its understanding of international relations. As with all other forms of realism, neorealism centres itself around four key propositions (Wohlforth, 2009, p.132) to describe the international system.

First, realists view the nation-state as the most crucial human grouping (Wohlforth, 2009, p.132) rather than ideas of international institutions. Secondly, narrow self-interest (such as expansion or preservation) governs the actions of states (Wohlforth, 2009, p.133). Thirdly, realists view the international system as anarchical, meaning the absence of a global governing structure forces states to help themselves (Wohlforth, 2009, p.133; Waltz, 2000 p.33). Finally, the three proceeding propositions force international relations into a system of power and security (Wohlforth, 2009, p.133). After these building blocks of all realist theories, the divergence from classical realism towards an independent approach of structural realism begins, and it is this which I now move on to.

Neorealism concentrates much of its theorising around one central idea. That “a rational state never lets its guard down and adopts a worst-case perspective and always aims to balance capabilities of potential aggressors” (Brooks, 1997, p.448). Such an idea builds upon the fundamental concept of states existing within an anarchical system (Waltz, 2000, p.33), essential to classical realism. However, the difference in the case of neorealism is that its proponents view conflict as an inevitability caused by the international structure (Wohlforth, 2009, p.135) rather than one driven by domestic and human factors as is the case with classical realism. It is this centralisation of the global system, which differentiates neorealism from its classical counterpart.

Building upon claims of the structural causation of conflict, neorealism argues the conditions of anarchy in the international system forces states to adopt the worst case/possibilistic assumption (Brooks, 1997, p.449). This assumption rests on the idea that, given the presence of a self-help system, within which the actions of other states cannot be determined with certainty, states will take defensive measures to ensure that potential aggressive action can be pre-emptively avoided (Brooks, 1997, p,448). Kenneth Waltz surmises this idea by claiming that the cause of war can be “anything” (2000, p.8), and thus providing the belief that, by assuming (and preparing for) the worst, states ensure their continued survival. Neorealism presents three exemplar forms of attempts to ensure survival can take, all of which become offshoots of neorealist theory themselves.

The first of these strands (and the one which this essay shall use to argue the relevance of neorealism to space militarisation) is that of offensive realism. This offshoot from neorealism sees the structural nature of the international system (anarchy) as innately conflict generating, requiring states to strengthen their capabilities to counter the perceived threat that the structure causes (Wohlforth, 2009, p.139). A lack of enforcement mechanisms upholds this structure and the secrecy, which is relied upon by states (Wohlforth, 2009, p.139). Such perceptions and approaches are often manifested in an inherent suspicion of the opposing state, which further causes ever-increasing offensive capabilities (also often referred to as the security dilemma (James, 1995)).

The second is the idea of defensive realism, which is best described as taking the opposite view to offensive realism. This is manifested as taking limited and restrained action to limit the risk of conflict (Wohlforth, 2009, p.139). This restrained approach is caused by several features of the international system, most notably the idea of nationalism within the state structure, making the conquest of territory significantly harder (Wohlforth, 2009, p.139). As such, states are encouraged to limit attempts at expansion to protect their security against any potential adversary. Therefore, this follows the idea of protecting security interests rather than maximising power.

Finally, one attempt to link both approaches is the “balance of power theory”, which argues that states will attempt to counter power concentration by balancing their military power with the adversary (Wohlforth, 2009, p.141). As may be seen from this theory, its broad reach means that it can be applied to both offensive and defensive realism as it is not a theory of military build-up but instead focuses on capability balancing.

This section has outlined the fundamentals of neorealist theory; the following paragraphs shall critically analyse the approach by looking at the internal debates within the realist tradition.

Debates within realist theory

There are numerous debates within realist theory, and this section examines them. Furthermore, this section will bring a critical lens to the ideas of neorealism to determine the sustainability of its claims.

Before continuing to the more in-depth debates within realist theory, it is essential to recognise the discussion surrounding offensive and defensive realism. Given their development as opposing understandings of the nature of the international system and conflict within it (Wohlforth, 2009, pp.140-141), it is unsurprising these two approaches are in constant disagreement. It is outside the capabilities of this essay to fully develop the integrity of each of the claims these two approaches take, so it shall instead briefly outline the core benefits offensive realism provides compared to its defensive counterpart.

Given the consistent high-security pressures of the international system (Brooks, 1997, p.447) and the absence of a supreme authority governing the actions of each member of the global system (Brooks, 1997, p.448), it is reasonable to suggest that each state would be fearful of the intentions of potential adversaries. Furthermore, despite claims that restrained behaviour can ensure security (Wohlforth, 2009, p.139), significant powers will often use an unwillingness to build up military force against a state rather than a de-escalating attempt, supporting the need to strengthen one’s defences as argued by offensive realists.

This essay must also examine fundamental differences between classical and neorealism as well as make the critical point that, despite the claims of some of its critics, realism has never been a single theory (Wohlforth, 2009, p.131). Yet, it is this very diversity that makes it so significant in understanding the international system.

There are several debates within the tradition of realism; the most prevalent is the idea that neorealism does not “move beyond the human nature arguments of classical realism” (Brooks, 1997, pp.449-450). Whilst this is true as a critique of neorealism, it fails to recognise that realism as a tradition has never been a single homogenous theory but has instead been a grouping of wide-ranging ideas (Wohlforth, 2009, p.131). Therefore, the claim that neorealism does not move beyond classical realism fails to recognise that classical realism has always been the basis for theoretical developments within the tradition.

Finally, critics claim that neorealism cannot provide a theoretical understanding of which system is more likely to be war-prone (James, 1995, p.186), and the ideas of classical realism (particularly that probability of conflict according to factors other than the distribution of capabilities (Brooks, 1997, p.457)) fundamentally undermine the arguments of neorealism. While these ideas do run counter to the theories of neorealism, these claims once again fail to recognise that neorealism forms a part of the broader ideas of classical realism and uses them as building blocks rather than attempting to disprove them (Waltz, 2000).

Furthermore, the first criticism of neorealism outlined above ignores the fundamental understanding of the system by neorealists who claim to examine war not based on probability but as a constant possibility (Brooks, 1997, p.448), hence the persistence of the worst-case possibility outlined in the previous section. This is also something that has been consistently proven, and the next section of this essay shall provide evidence.

To conclude, this section has outlined some of the most significant criticisms of neorealist theory, focussing primarily on those most relevant to the example this essay uses. This essay shall now explore this example and the relevance of neorealism to understanding its importance.

Astropolitics, neorealism, and the militarisation of space

The 1957 launch of Sputnik 1 by the USSR and the subsequent deployment of satellites by the United States and other nations led to the initial development of anti-satellite (ASAT) technology in the 1960s (Bormann and Sheehan, 2009). When examined in the modern-day, it has been claimed that “Who controls low-Earth orbit controls near-Earth space. Who controls near-Earth space, dominates Terra [Earth and atmosphere]. Who dominates Terra dominates the destiny of humankind…” (Moore, 2011, p.643). For this reason, ASAT development has continued, and neorealist theory (including offensive realism) continues to be relevant.

Looking more closely at the specifics of space militarisation and neorealism, using the principles of offensive realism, it is possible to see how space becomes dominated by neorealist principles. While space has not yet been weaponised (Moore, 2011, p.643), increased number of military capability tests (Moore, 2011, p.654) (for example, ASAT technology) and continued use of space for military activity (such as placing surveillance satellites in Low Earth Orbit (LEO)) (Henry, 2008, p.61) show a real-life persistence of the idea of power balancing within the international system. For example, the Chinese testing of ASAT capabilities in 2007 (Al-Rodhan, 2018) can be seen as attempting to counter the hegemony of US military capabilities in space. This claim is outlined by offensive realism in claiming an opposing power will build up the military capability to counter an opposing force.

When examining the possibility of conflict in space, the inevitability espoused by the ideas of neorealism is almost perfectly identifiable. The destabilising effect of continued space militarisation (Henry, 2008, p.62) coupled with the ever-increasing potential for exponentially increasing damage from space debris from ASAT testing and the increased use of space more generally (Moore, 2011, p.650) pose a serious risk of causing conflict unintentionally. When this is examined alongside the lack of a unanimously ratified legal framework (Moore, 2011, p.654), it is easy to see how the potential for conflict is continually increased.

When considering attempts to limit the risk of conflict within the realm of outer space, the benefits of a neorealist approach can once again be seen. The creation of the Outer Space Treaty and the Committee on Peace Uses of Outer Space (COPUOS) attempted to formulate an international structure, within which to govern the uses of space (Hickman, 2019, p.184) and present attempts, which have fundamentally failed in their purpose (Hickman, 2019, p.184; Bormann and Sheehan, 2009).

Whilst attempts to prevent nuclear weapons of Mass Destruction (WMDs) from reaching outer space have succeeded, loopholes within the agreements (and the lack of unanimous ratification, including by major space powers) allow for the continued use of conventional munitions in space (Al-Rodhan, 2018). Such accounts support claims made by neorealist theorists that international institutions have a negligible effect on states’ affairs, instead focussing on power and security due to the nature of the international system. This section has outlined just some of the arguments on how neorealist theory (and the theory of offensive realism) can be applied to the ideas of space militarisation as a modern international phenomenon. 


To conclude, the purpose of this essay has been three-fold. First, it has outlined neorealist theory’s fundamental arguments, particularly where it aligns with classical realism and its key differences. Secondly, this essay examined the key internal debates, which were of relevance to this essay, most notably the debates surrounding offensive and defensive realism, claims surrounding its lack of addition to the broader school of realism, and finally, its lack of explanation of the war-prone nature of the international system. This second section provided challenges to each of these claims to prove neorealism’s importance in modern IR theory. Finally, this essay applied the critical arguments of neorealism to explain the militarization of space in modern international relations.


[1] Formally: “Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies”


Al-Rodhan, N. (2018) Weaponization and outer space security. Available at: (Accessed: 12 November 2021).

Bormann, N. and Sheehan, M. (2009) Securing outer space. Oxford: Routledge.

Brooks, S. G. (1997) ‘Dueling realisms’, International Organization, 51(3), pp. 445–477.

Dolman, E. C. (1999) ‘Geostrategy in the space age: An astropolitical analysis’, Journal of Strategic Studies, 22(2–3), pp. 83–106.

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Henry, p. (2008) ‘The militarization and weaponization of space: Towards a European space deterrent’, Space Policy, 24(2), pp. 61–66.

Hickman, J. (2019) ‘Research vewpoint: International relations and the second space race between the United States and China’, Astropolitics. Routledge, 17(3), pp. 178–190.

James, P. (1995) ‘Structural realism and the causes of war’, Mershon International Studies Review, 39(2), pp. 181–208.

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Pfaltzgraff, R. (2013) International relations theory and space power. Available at: (Accessed: 12 November 2021).

Waltz, K. N. (2000) ‘Structural realism after the Cold War’, International Security, 25(1), pp. 5–41. Wohlforth, W. C. (2009) ‘Realism’, in The Oxford Handbook of International Relations, pp. 1–20.

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