Military Alliances in the Twenty-First Century. Alexander Lanoszka

made by their weaker members, then what explains them? Why, to reiterate the puzzle, is the United States able to accumulate so many allies? Geography is one possible explanation. Specifically, the United States is separated from most of its allies by oceans. Thanks to physical distance, allies have less reason to fear it and so they are much more concerned with threats closer to home. They can leverage support from Washington to help deter nearby adversaries. The problem with this explanation – intuitive though it may be – is that geography is a double-edged sword. The United States may be less threatening because it is far away, but it may also be less militarily useful – and perhaps even unreliable – because it has to make up a lot of distance if it wishes to fight an adversary alongside a far-flung ally. Moreover, geographically contiguous states can be allies, and very good ones at that. Canada may fear the domination of US cultural products in its own domestic marketplace; it can even be anxious about preserving its own autonomy. Nevertheless, it does not fear a land invasion given that it engages in defense cooperation with the United States (Bow 2009). Joseph Jockel and Joel Sokolsky (2009: 323–4) even argue that Ottawa enjoys an “involuntary guarantee” from Washington because so many Canadians live close to the US border. In Central Asia, states such as Kazakhstan participate in the CSTO, of which Russia is the most powerful country. They too worry about their autonomy vis-à-vis the Kremlin, but they still willingly engage in some joint military exercises and other forms of military-to-military cooperation (Costa Buranelli 2018: 389). Of course, geographically contiguous allies may sometimes lack agency and be subject to domination because the powerful state projects a preponderance of power over them. At the beginning, many Warsaw Pact countries took directives from Moscow in part because the local presence of commissars and the Red Army had an outsized impact on local domestic politics (see Rice 1984). Geography is not destiny.

      There are, of course, benefits in allying with a weaker state. The example of the Soviet bloc suggests how political control over domestic and foreign policy can be one such benefit, but again such control is often incomplete and can dissipate over time (Cooley and Spruyt 2009). A second benefit is to acquire so-called defense-in-depth. In military parlance, defense-in-depth refers to a strategy where an attacker must confront successively robust layers of defensive points designed to absorb the first blow, delay the attacker’s forces, and buy time for the defender to respond. A third, cruder benefit is that allies can be buffer states if they provide a battleground away from the territory of the great power where fighting with the adversary will first take place. The Soviet presence in East Germany and Poland offered Moscow this defense-in-depth against Western Europe, which it did not really have prior to the Second World War. Still, a defense-in-depth strategy or a buffer zone is no good if allies wrangle with each other. In cases where allies have a history of acrimonious relations with one another, extending security guarantees to each of them can help diffuse tensions by reassuring them both that their interests are heeded. The US military presence in Europe has, arguably, had this stabilizing effect. By becoming a European power in its own right during the Cold War, the United States inserted itself between France and West Germany, allaying concerns that the historical antagonisms they had for each other could resurface and would lead each to take up their disputes with military force again.

A fourth possible benefit to military alliances is that they facilitate such military cooperation as joint military exercises, interoperability, and personnel exchanges. Military alliances are not entirely necessary in order to create this particular benefit, but they can provide an institutional foundation for their continuous and regular operation. True interoperability requires reducing uncertainty and so can benefit from technological transfers, unified command systems, intelligence sharing, and other cooperative endeavors that allies would not consider doing for those that they fear would almost certainly renege on their pledges. Of course, these institutional foundations may or may not be of service if the great power needs to cobble together a coalition of states to undertake a military campaign. As Chapter 5 highlights, major problems of interoperability can persist and hamper those military operations that even longstanding allies undertake. Finally, having an ally on one side may in some cases be better than having it in the enemy’s camp. For example, the ally might be positioned near key waterways or other sites of strategic interest that could be useful for projecting power in a wartime situation. Turkey has been consistently valuable to NATO precisely because of its location vis-à-vis the Dardanelles and the Bosporus. Put together, it is unclear whether great powers really do give up their security to weaker states if such arrangements can augment their sense of security as well.

A version of the concession-extraction argument holds that alliance formation can result from an expansionist foreign policy that is pursued for its own sake. This sort of argument has gained currency in recent years among those critics of US foreign policy who allege that Washington has taken on too many alliance commitments as part of a global liberal crusade or hegemonic project (Posen 2014; Mearsheimer 2018). Allies might not necessarily have made concessions, to be sure, but alliances still serve to project influence in the pursuit of a grand ideological initiative. As an explanation for alliance formation, this thesis overlooks how the United States has been uneven in advancing liberalism abroad (Jervis 2020: 18–19). After all, Taiwan is a successful liberal democracy but receives no such treaty commitment from the United States despite Taipei’s eagerness to have one. Nevertheless, it is possible that the United States emerged from the Cold War victorious and with so much power that it sought to exploit the situation by trying to widen its authority even more (Mearsheimer 2018). Again, if Washington aimed at achieving global hegemony, then the willingness of small states to jump on that bandwagon rather than oppose it still requires explanation. Part of the answer may be that, for democratic states especially, the United States is an attractive partner because its democratic constitution and willingness to use international institutions, however selective this may occasionally be, make it less likely to dominate other states (Ikenberry 2001). But even this explanation is incomplete. Not only should the United States be nonthreatening to potential allies, but, as the previous discussion suggests, those potential allies should likely perceive to some degree the same threats that the United States perceives.

But Why Have an Alliance Treaty?

A major weakness of both sets of arguments discussed above – that alliances are formed to face threats and help states to extract small power concessions (and thus to gain influence) – is that they leave unexplained the existence of a treaty. States can collaborate in face of a threat without having to sign a treaty. Alarmed by Iran, the countries of Israel and Saudi Arabia have improved their ties despite the historical animosity that they felt for one another. Their security personnel and their defense officials have met on multiple occasions. Saudi Arabia has apparently signaled its “willingness to provide Israel an air corridor and air bases for rescue helicopters, tanker aircraft and drones in case Israel decided to bomb the Iranian nuclear facility” (Abadi 2019: 444). No alliance seems probable between them, however. Similarly, uneasy about the rise of China, Vietnam has signed memoranda of understanding and enhanced defense cooperation with Australia and Japan, but has so far not signed an alliance treaty with either (Liff 2016: 450). In the book in which he advances the theory that states forge alliances to balance threats, Walt (1987) considers both formal treaty alliances and informal alignments. As I highlight in Chapter 5, many coalitions of states have been formed in wartime and fought effectively against their adversaries, despite not having an alliance treaty beforehand. Leaders of states should just as easily be able to communicate their intention to stand firm against an adversary through public statements. In this vein, US President Franklin Delano Roosevelt pledged to defend Canada in a thinly veiled reference to Nazi Germany when he accepted an honorary doctorate at Queen’s University in Kingston, Ontario, in 1938 (Granatstein 2020: 145).

      Strong states should not have to sign treaties if they wish to extract concessions from smaller states. They should be able to do so by dint of their strength alone, in keeping with the oft-repeated notion that “the strong do what they can and the weak suffer as they must.” Strong states presumably have options other than alliance commitment if they wish to safeguard another state from external attack. As the United States did with Saudi Arabia between the 1990–1