“If Hitler invaded Hell I would make at least a favorable reference to the Devil in the House of Commons” (Winston Churchill, The Grand Alliance [1950] 2010, p. 331). While this famous quote by Churchill is not found in the book (a variant by Kenneth Waltz is used as an opening epigraph), it perfectly captures the main idea of Evan Resnick’s Allies of Convenience. Britain and the United States allying with the Soviet Union during World War II is just one example of a broader phenomenon: a state aligning with a partner with which it has ongoing national security conflicts (such as both seeking control over the same region) and divergent political ideologies (such as a liberal democracy and an illiberal autocracy). Resnick labels these pacts “alliances of convenience.”

For such pacts to exist, it is critical for a third party to pose a threat to both states. This is unsurprising, as George Liska (Nations in Alliance: The Limits of Interdependence, 1962, pp. 12–13) taught us long ago that “alliances are against, and only derivatively for, someone or something.” In the case of Britain and the United States aligning with the Soviet Union, the shared threat was Nazi Germany. The shared threat can also change, as has been the case for the long-standing alliance between the United States, a democracy, and Saudi Arabia, a nondemocratic monarchy. For these allies, the shared threat ran from Nazi Germany, to the Soviet Union, to Saddam Hussein’s Iraq, and then to Iran under the Ayatollah. Because of these shared threats, the United States has tolerated Saudi Arabia’s pursuit of policies that are viewed as against US interests, such as the Obama administration’s reluctant support for Saudi forces in Yemen, and the Trump administration’s willingness to look the other way after the Saudis’ state-sponsored murder of Jamal Khashoggi.

Resnick’s goal is to understand why the United States fails to properly manage these allies. More precisely, while the United States has formed a number of “alliances of convenience” since World War II (a useful table is found on p. 22 of the text), Resnick observes that it nearly always makes big concessions to the other state, even when these concessions run counter to US national security interests or adherence to democratic norms. These concessions reflect a weak position of the United States within these alliances. For Resnick, this is puzzling from the standpoint of two main theoretical approaches to alliances: what he terms “neorealism alliance theory” and “Tying Hands theory.” Both theories predict that the United States, with a favorable balance of power and constrained executive, should secure the better end of a bargain when negotiating to form an “alliance of convenience.” The former theory builds on the work of Glenn Snyder and Kenneth Waltz. It holds that bargaining outcomes between allies will largely be determined by the relative power of the parties. The latter theory builds on classic bargaining theory, as found in Thomas Schelling’s classic Strategy of Conflict (1960) and Bob Putnam’s “two-level bargaining” models of international negotiations (“Diplomacy and Domestic Politics: The Logic of Two-Level Games,” International Organization, 42 [3], 1988). This theory argues that a state whose leader is constrained domestically will be able to secure a good deal from a foreign government.

Because neither theory offers insights into the United States’ weak bargaining position within “alliances of convenience,” Resnick draws on ideas from neoclassical realism to put forward an alternative argument. Key to his argument is that the foreign policy executive must appease domestic groups who oppose the alliance. This entails portraying the prospective ally in a positive light: think of Joseph Stalin being referred to as “Uncle Joe” in the United States during World War II. Because this strategy necessarily involves minimizing the geopolitical and ideological differences between the two countries, portraying the ally positively complicates the foreign policy executive’s ability to demand fundamental policy changes from the ally.

Resnick’s explanation is sensible, but it also raises a couple of questions. First, why can’t the foreign policy executive put on a “happy face” to domestic audiences, but drive a hard bargain at the negotiating table? Is it because the prospective ally knows that there is no way for the foreign policy executive to “name and shame” its unwillingness to make concessions? Second, aren’t there more straightforward alternative explanations? In particular, is the strong state’s weak bargaining position vis-à-vis “allies of convenience” simply because the prospective allies are, well, convenient? In other words, could it be that the strong state’s weak position occurs because there are few (if any) alternative allies? The strong state likely aligned with the ally because the ally was engaged in military hostilities with a bigger threat or was one of the few states in a particular region willing to stand up to a bigger threat.

Consider some key US allies in the Middle East region. The United States has tolerated behavior by Saudi Arabia that goes against US interests in the region and against US democratic values. Is this because the United States is facing strong domestic opposition against Saudi Arabia, or is it because the US government has few viable alternatives to countering larger threats to the region? Consider also Israel and Turkey, two other US allies in the region. While not listed as “allies of convenience” in Resnick’s table (though one wonders if Turkey should be on that list), both leverage their unique positions in the region to gain US acquiescence to policies that may otherwise run counter to US regional interests.

Another straightforward alternative is suggested in a second new book on alliances, Marina Henke’s Constructing Allied Cooperation: Diplomacy, Payments, and Power in Multilateral Military Coalitions (2019). For Henke, the United States must overcome international reluctance to a questionable foreign policy action. Like Resnick, Henke also focuses on US bargaining with prospective allies. But unlike Resnick, Henke is interested in understanding the bargaining tactics used by the United States to form military coalitions, such as the US-led United Nations Coalition in the Korean War or the coalition that invaded Iraq. For Henke, a key bargaining tactic of the United States is the offering of side payments, which can literally be monetary aid (what was once cynically referred to as the “coalition of the billing” with respect to Iraq). Because some countries are reluctant to join the United States on a potentially misguided foreign policy adventure (or might wish to bandwagon with a threat), the United States must buy allies to create its coalition. While this underscores Resnick’s point that the United States was in a weak bargaining position, the mechanism explaining that weak bargaining position is different. One wonders what Resnick makes of these alternative explanations for how “allies of convenience” are created and how they comport with his own description of this phenomenon.

In the book, Resnick evaluates his preferred explanation by applying process tracing to three case studies: the alliance with the People’s Republic of China against the Soviet Union (1971–89), the alliance with Pakistan against the Soviet Union in Afghanistan (1981–88), and the alliance with Iraq against Iran (1982–88). Though the cases are well chosen to control for common domestic characteristics, such as Republican presidents with strong foreign policy credentials, Resnick expresses concern about selection bias; namely, that he is selecting on the dependent variable by only studying alliances of convenience. I am less concerned about this problem. If Resnick wished to explain why states form alliances of convenience, then variation on the dependent variable would be important. But Resnick’s study seeks to identify the plausibility of a process: he seeks to know the mechanism explaining why the US position within such alliances is relatively weak. We know that the United States has a weak position within its alliances of convenience, and we also know that, for each of these alliances, the United States has had notable and vocal domestic critics. Hence, the question is whether the need to appease domestic opponents or some alternative process (such as those listed earlier) explains the US’s weak position in its alliances of convenience.

Resnick’s book nicely builds on the tradition of Jeremy Pressmen’s Warring Friends: Alliance Restraint in International Politics (2011) and Patricia Weitsman’s Dangerous Alliances: Proponents of Peace, Weapons of War (2004). It does so by making plain that one must not confuse “allies” with “friends” or even “partners.” Allies exist for reasons of war fighting and balance of power; alliances can often be temporary marriages that bring together states with otherwise opposing views. In this sense, Resnick’s book hearkens back to the famous phrase by Lord Palmerston that “there are no permanent friends or permanent enemies, only permanent interests.”