Military Alliances in the Twenty-First Century. Alexander Lanoszka

a decade after these pronouncements were made, military alliances began to experience a revival. Seth Cropsey (2020) of the Hudson Institute has argued in favour of “[s]trengthening the US–Taiwan Alliance [sic]” in order to improve regional defense against an increasingly powerful China. At least one scholar argues that China is “on the verge of an alliance” with Russia (Korolev 2019). In the spring of 2020, India and Australia signed a mutual logistic support agreement that would allow each country to access the other’s military balance, signaling that they may be involved in more military exchanges and exercises in the future. Already across the Indo-Pacific region a patchwork of different security relationships has taken shape between countries that have previously avoided military cooperation, suggesting that new defense pacts may yet form with the goal of managing the rise of China and its attendant challenges (Simón et al. 2021). Though admittedly more of a case of alliance enlargement than of alliance formation, the United States added two new treaty allies to its roster, with Montenegro and North Macedonia joining NATO in 2017 and 2020, respectively. Indeed, the security challenge posed by Russia following its annexation of Crimea from Ukraine reanimated NATO. Some alliance scholars have spoken of how NATO could contribute to balancing efforts against China (Moller and Rynning 2021: 185). Whereas London and Washington may have had a “special relationship” in the twentieth century to confront threats in Europe and elsewhere, Tokyo and Washington may yet have one in the twenty-first century on the basis of their Security Treaty as the center of gravity in international affairs shifts toward the Indo-Pacific.

      The standard view is that states establish military alliances for at least two, non-mutually exclusive, reasons. The first is that states wish to balance against a threat that they commonly face. The second motive is that strong states use the alliance relationship as a vehicle for expanding their influence over others. This is supposed to be especially true of asymmetric alliances, in which at least one member is significantly greater in military and economic capabilities than another. In these arrangements, the stronger state is able to extract key concessions from its weaker counterpart.

      As this chapter illustrates, however, the problem with these standard arguments about alliance formation is threefold. First, although threat-based arguments provide a powerful explanation for why states form alliances, they remain insufficient in accounting for the patterns that we see, for the simple reason that shared threat perceptions do not always lead to formal alliances. No one set of factors will ever systematically lead states to sign an alliance, in part because alliances are costly. States sometimes might not wish to get exposed to the disputes of potential allies. Second, existing understandings overstate the concessions that even great powers can extract from weaker states by way of a treaty. And third, the foregoing explanations of alliance formation do not explain why a written alliance treaty is actually a necessary condition for achieving such ends as balancing and concession-extracting. This chapter argues that a signed alliance treaty is desirable not just for defining the terms of a commitment, but also, ironically, for injecting a certain amount of vagueness into the language of the agreement itself. Alliance treaties thread the needle between certainty and ambiguity, permitting states to be more comfortable about deepening their military cooperation, if they choose to do so.

Uncertainty, Violence, and Political Difference

Any discussion of why states establish alliances must begin with at least three observations about international politics. The first is that states form and sustain their military alliances in an anarchic international environment. No higher governmental authority exists above the state – none that can make and enforce rules that states would feel, for whatever reason, they have little choice but to obey. Accordingly, states are uncertain about the intentions of others, be they allies or adversaries, because the absence of a higher authority compounds the difficulties of getting reliable information about what others are planning to do. There is lively scholarly debate about the nature of uncertainty in world politics (see Rathbun 2007) or the meaning of anarchy (see Nedal and Nexon 2019), but the point is that some degree of uncertainty ultimately exists in international relations.

      The second observation is that violence not only is possible under anarchy, but can, in the extreme, lead to the elimination of a state or its governing political system (Fazal 2007). This potential for violence raises the stakes for international cooperation. Some states may be able to wield sufficient capabilities that they can defend against most threats without needing the support of others. Most states are not so fortunate and thus may have to seek outside assistance in order to get a handle on the challenges that they face. Precisely because of the high stakes that are involved, alliance decisions can be emotional, sometimes turning on fear, distrust, and even anger. That alliance politics can have a strong emotional dimension does not automatically imply irrational behavior. A park visitor would be right to be afraid of a hungry grizzly bear in his or her path, but some responses to mitigate that danger are more sensible than others.

The third observation is that states have different interests that they wish to advance in their foreign policymaking. Of course, many states want the same things: territorial integrity, freedom to determine their foreign and domestic policies, economic prosperity, higher welfare for their citizens, and safety from harm. Nevertheless, that interests often overlap does not imply that states are all favorably predisposed to the status quo or that they interpret the status quo in the same way. Their leaders might have conflicting beliefs on how to obtain those goods – some might even be hostile to the status quo, valuing expansion over security (Schweller 1996: 106–7). Alternatively, states might value the same things but have different priorities, creating disagreement over which matters most. Because we live in a world of scarcity, whether in terms of material resources, time, or attention, states must make choices about which capabilities to develop and how they should use them to achieve their desired ends. Compounding these issues is the problem of modernity, which John Ikenberry (2020: 14) describes “as the set of deep, worldwide transformations in domestic and international society unleashed by the forces of science, technology, and industrialism” that began in the eighteenth century. Modernity means that different societies, and the states that govern them, can exhibit varying levels of development and so have contrasting preferences or ideas on how to achieve wealth and prosperity. Such discord can exist despite how, or perhaps because, societies around the world have become increasingly connected with one another. How to organize relations in such a complex global system itself can be an object of contention. International politics, in a nutshell, is about states often having conflicting interests and values in an environment where violence is possible, where no overarching supreme authority is available to act as a referee.

These three basic observations about international politics do not imply a single theory for what drives alliance formation. After all, military alliances can be either offensive or defensive. Offensive alliances, which help states coordinate an attack against others, are relatively simple to grasp. Jack Levy (1981: 590) finds that military alliances were often offensive prior to 1815, with their founding treaties calling for the use of force even in the absence of an external military attack. Following the Napoleonic Wars (1803–15), the offensive alliance became a very rare form of international political organization, at least as far as the public record is concerned. Still, according to Randall Schweller (1994: 79, 87), states sometimes bandwagon for profit, forming offensive alliances with a more powerful state to “share in the spoils of victory” as well as “to improve their position.” For example, the leaders of Austria, France, and Spain came together in 1508 as the League of Cambrai in a bid to divide Venetian territory amongst themselves. Fascist Italian leader Benito Mussolini overcame his initial reservations about Adolf Hitler and signed his country to the Pact of Steel with Nazi Germany in March 1939. Though blindsided by the German invasion of Poland later that year, Mussolini participated in the Battle of France after some delay in June 1940. In each case, leaders held a shared belief that the status quo was undesirable and that their partnership would allow them to revise it in a mutually satisfactory manner.

The vast majority of military alliances are defensive in character, however. Yet the notion of a defensive alliance is a misnomer, for defensive military alliances do not serve to fight defensively as much as they serve to deter war. Indeed, defensive military alliances practice extended deterrence. Deterrence refers here to how military