In January 2020, the United States conducted a targeted air strike against Iranian Quds Force commander Qasem Soleimani. White House officials publicly stated that the strike was meant to deter “future Iranian action” against American targets. Yet, Iran quickly retaliated by launching missiles against two Iraqi military bases housing American personnel, injuring over two dozen American soldiers. While the Soleimani strike was successful in killing its intended target, it failed to achieve its broader strategic and coercive goals. Rather than deterring Iran, the strike had the opposite effect. The United States hoped its show of limited force would communicate its resolve—or determination to achieve its goals—with regard to Iran. However, the Trump administration's muted response to Iran's reprisal demonstrated a lack of commitment and may have undermined the president's and America's reputation for resolve precisely because the administration did not react decisively despite its earlier threat meant to deter Iran.Footnote 1 This is problematic, as actors that carry reputations for lacking resolve may find it more difficult to issue credible threats in the future and to signal their seriousness and commitment to a course of action, and as a result may even become easier targets of aggression from adversaries. Why then did the administration choose to implement a limited air strike when it was unwilling to later follow up on its threats when deterrence failed?
Limited air strikes present an enticing coercive option for policymakers for several reasons. They are less costly than other forms of militarized force, such as broader air campaigns or deploying ground troops; yet, they are more potentially costly than nonmilitarized acts, such as sanctions. Limited air strikes also provide the opportunity to escalate with further military force based on the target's response. Policymakers thus believe that limited air strikes can signal their resolve and coerce other states into changing or ceasing their behavior. Accordingly, this middle-ground approach allows policymakers to act without taking too much political or military risk.
Limited air strikes, however, are not the elegant solution policymakers are hoping for. Even when limited air strikes are militarily successful, they often fail to accomplish their intended political goals.Footnote 2 Such was the case for Trump's use of a limited air strike against Iran. In this essay, I focus on the use of limited air strikes for coercive purposes. I explain why policymakers prefer limited air strikes to other types of force and show how for the same reasons that policymakers choose limited air strikes, their efficacy is reduced as a coercive tool. The fact that limited air strikes are less costly for the coercer undermines the ability of leaders to signal their resolve—and their willingness to pay the costs to achieve their stated goals.Footnote 3 Accordingly, coercers threaten to employ them because they are less costly; yet, the less costly nature of limited air strikes undermines their ability to clearly signal the coercer's resolve and reduces the likelihood that such threats will coerce the target. If coercers then back down and fail to follow through on their threats, they face reputational costs—particularly from outside observers, including potential adversaries.
However, if coercers do carry through on their threats, they risk reprisals and/or escalation from the target and then must decide whether to back down or to escalate the conflict further,Footnote 4 both of which are nonpreferred options that carry further reputational costs. Thus, while limited air strikes may seem attractive, they are not a good option for coercive purposes. Finally, I explain what this quagmire means for the ethics of using limited air strikes as a coercive tool, particularly as limited air strikes fall under the category of jus ad vim. Here, I specifically address how these reputational costs undermine the principles of right intention, likelihood of success, and probability of escalation.
Why Leaders Choose Limited Air Strikes as a Tool of Coercion
Part of the appeal of limited air strikes lies in the fact that they are a less costly form of force for the coercer, particularly when compared with the alternatives of broader air campaigns or deploying troops on the ground.Footnote 5 Because they are less costly, limited air strikes require less public support than other forms of military engagement.Footnote 6 Limited air strikes are also highly flexible, as their “range and versatility allow [them] to be launched from a number of countries” in a short time frame.Footnote 7 The surgical nature of many limited air strikes makes them an attractive method for decapitation strategies, although evidence is mixed as to whether such strategies achieve broader political goals.Footnote 8
Limited air strikes are also a theoretically more proportional response than other types of force, as they can be employed tactically to reduce the number of casualties on the ground.Footnote 9 President Trump, for example, justified his April 2017 air strike against Syria in response to the use of chemical weapons by clarifying that the strike was limited “to the air base in Syria from where the chemical attack was launched” and was intended to “prevent and deter the spread of and use of chemical weapons.”Footnote 10 In addition, policymakers believe that limited air strikes demonstrate their resolve, showing outside observers that they are not afraid to act. After all, the decision to employ any kind of force should be a signal of a leader's willingness to fight, and such signals of resolve are necessary for threats to be credible.
Policymakers may hope they will not need to actually engage in limited air strikes for their demands to be met. In an ideal coercive scenario, the mere threat of limited air strikes will be enough for the target to acquiesce to the coercer's demands. As Schelling teaches us, “Violence is most purposive and most successful when it is threatened and not used. Successful threats are those that do not have to be carried out.”Footnote 11 Coercers would strongly prefer to threaten military action as a first step and then only follow through on those threats when necessary. Limited air strikes provide an especially appealing threat for the coercer. Threats of military force should be more credible, and thereby more likely to succeed, than nonmilitarized threats because they carry a larger risk of damage to the target as well as an increased risk for the coercer. This, coupled with the relative lack of public constraints on carrying out limited air strikes, as well as their relative ease of use for many states, makes the threat of limited air strikes a particularly attractive coercive option.
Why Limited Air Strikes Are a Poor Coercive Tool
The same factors that make the threat and use of limited air strikes appealing also undermine their efficacy as a coercive tool. In order for coercion to be successful, the target must believe the coercer is resolute and that its threats are credible. The coercer needs to demonstrate that it is “willing to incur costs” to acheive its goalsFootnote 12 and that it will follow through on its threats if the target fails to acquiesce to its demands.Footnote 13 In order to communicate resolve, coercers need to employ costly signals—or actions that are potentially damaging to them in political, economic, and/or military terms. Without such costly signals, the coercer fails to show the target it is truly resolute. The costliest signals are typically associated with putting a state's own troops or public in harm's way, as these actions carry the largest potential political and military costs to the coercer and should therefore be the strongest signals of its resolve. Limited air strikes typically protect the state's own military and public from harm, generally making them a weaker signal of resolve.
Limited air strikes thus often fail to communicate resolve precisely because they are less costly for the coercer, especially when compared with other forms of militarized action. By implementing limited air strikes, the coercer reduces the number of potential casualties faced by its personnel, especially if it employs drones. The limited nature of such air strikes can also signal an unwillingness to commit the necessary economic, political, and military resources that it takes to go to war.Footnote 14 Limited air strikes are typically less politically costly for policymakers, as they do not require the same amount of public or allied support as other military operations.Footnote 15 Further complicating matters is the finding that air power, more generally, is viewed as less costly for policymakers than deploying ground troops or using other types of military force.Footnote 16 Even more extensive air campaigns are viewed as “the ‘cheaper’ military option compared with land and naval power” because they are often more limited than other forms of military force, require fewer resources on the part of the coercer, and have a lower risk of military casualties for the coercer.Footnote 17 Accordingly, air campaigns have acquired “a reputation for being preferred by low-resolve states, unwilling to take on the casualties and other costs of ground intervention.”Footnote 18
The fact that even broader air campaigns are viewed as less costly than other forms of militarized force further undermines the notion that limited air strikes are a good option for demonstrating resolve, especially as the costs of limited air strikes are even lower than those of broader air campaigns. While one might presume that employing limited air strikes will signal more resolve than doing nothing or implementing nonmilitarized measures, observers often consider the choice to use limited air strikes in comparison with more extensive forms of force—not in comparison with nonmilitarized tools.Footnote 19 Accordingly, the choice to rely on limited air strikes signals that the coercer was unwilling to use other forms of force. This is not to say that limited air strikes are never effective in signaling resolve to outside observers, and coercers may believe that limited air strikes signal more resolve than simply doing nothing or engaging in nonmilitarized acts. But they also must be aware that the threat of action must be proportional to the coercive or political goal.Footnote 20 Militarized force is often reserved to achieve broader strategic objectives. On these issues, the threat or use of limited air strikes may actually signal a lack of resolve and an unwillingness to pay the costs associated with a longer-term military conflict.Footnote 21
Limited air strikes, therefore, may be most effective at signaling resolve on smaller and narrower issues or during noncoercive episodes. However, such air strikes are often used with the intention of achieving larger strategic and coercive goals, such as stopping Syria's use of chemical weapons or deterring Iranian provocation in the Middle East, to name two recent examples. In his testimony before the House of Representatives' Committee on Homeland Security in 2013, military scholar Stephen Biddle argued that limited air strikes were not only unlikely to achieve broader strategic aims in Syria but also would “inevitably allow others to read this self-limitation as a lack of resolve to finish the job” and would send an “ambiguous signal” regarding America's commitments in the region.Footnote 22 As a tool of coercion, therefore, limited air strikes are unlikely to coerce the target precisely because they signal a lack of resolve by the coercer, particularly for broader strategic aims.
The Reputational Consequences of Limited Air Strikes
This puts policymakers who threaten limited air strikes in a difficult position, particularly regarding the reputational costs of their coercive threats. As threats of limited air strikes are unlikely to effectively signal the coercer's resolve, these threats are less likely to be credible. Further undermining their credibility is the fact that the target can often absorb the relatively small costs or damage inflicted by such limited air strikes. Accordingly, targets are unlikely to be compelled or deterred by these threats. Coercers thus face a tough choice in how to proceed if their threats fail, with both responses carrying potentially negative ramifications.
Policymakers can back down and choose not to follow through on their threats. This may be an especially likely outcome if they threaten limited air strikes because they do not have a strong desire to actually initiate military action or because there is a lack of public support for more severe responses. However, in failing to follow through on their threats, leaders risk undermining their reputations for resolve. As I have shown elsewhere, leaders who make threats of militarized force but then fail to adequately back up these threats with actions when necessary acquire reputations for lacking resolve that leave them vulnerable to being targets of future threats of aggression.Footnote 23
Such was the case with the Obama administration's attempt to coerce Syria with the threat of limited air strikes. Then–secretary of state John Kerry framed the red line in terms of America's reputation for resolve and credibility: “It is directly related to our credibility and whether countries still believe the United States when it says something. They are watching to see if Syria can get away with it, because then maybe they too can put the world at greater risk.”Footnote 24 Obama's failure to follow through on his threats even after it was clear that Assad had violated the red line undermined his and America's reputation for resolve—not just vis-à-vis Syria but also with regard to the broader international community. For example, then–CIA director Leon Panetta and former secretary of state Hillary Clinton both argued that such actions negatively affected the president's personal reputation and America's reputation for resolve. Even more so, some have argued that Obama's choice to threaten limited air strikes to achieve “ambitious top-level goals,” such as removing Assad from power, further heightened the negative reputational consequences of his failure to follow through on his threat.Footnote 25 Furthermore, such reputational costs are not just limited to the United States. Former French president François Hollande, for example, also faced backlash for failing to follow through on his harsh rhetoric on Syria.Footnote 26
To avoid these reputational consequences, leaders may try to save face by justifying their decision not to act on their threats.Footnote 27 Yet, such spin can be difficult to employ convincingly, especially when policymakers have made explicit or precise threats.Footnote 28 Furthermore, leaders who engage in such behavior may acquire reputations not only for lacking resolve but also for being dishonest. This can further undermine their ability to credibly signal their intentions, thereby increasing the risk of crisis escalation in future disputes. Even when coercers choose not to follow through on their threats, targets or their allies may respond by escalating the crisis.Footnote 29 Coercers must then decide how to respond to such events, weighing the costs of protecting their reputations against the potential for larger-scale conflict.
Alternatively, policymakers can choose to follow through on their threats and employ limited air strikes. While this may be effective for meeting more-limited aims—such as punishing rivals or achieving specific military goals—it carries a host of complications when used for broader strategic or coercive purposes. Regardless, actually having to carry out the strikes is a suboptimal outcome for the coercer, as even resolute leaders would prefer to have their threats be effective without having to take military action. This pathway also risks unnecessary crisis escalation, as one cannot know how the target will respond to the use of force. Indeed, as Zenko explains, many military officials warn that the use of limited force not only has “little long-term impact on changing the adversary's behavior but can also have the inherently dangerous potential to uncontrollably escalate into a larger unwanted war.”Footnote 30 This, therefore, has the potential to directly undermine the jus ad vim principle regarding the probability of escalation, which states that actions that have a “high probability of resulting in war” may be difficult to justify.Footnote 31
Coercers may also choose to act on their threats and escalate the conflict in order to circumvent the negative reputational consequences of backing down. While such escalatory action can signal resolve,Footnote 32 it carries important ethical considerations, especially regarding the principle of right intention. And even if coercers prefer not to escalate the conflict, targets may respond to the threat of limited air strikes by escalating the conflict themselves. When this does occur, they face a choice between doing nothing—which carries reputational costs—or further escalating the crisis in order to demonstrate their resolve.
The Ethics of Limited Air Strikes for Coercive Purposes
Such a dilemma carries important ethical considerations regarding the threat of limited air strikes more generally. Ethically, these types of coercive threats lie within the realm of jus ad vim—a relatively new category of just war thinking that focuses on the use of force short of war.Footnote 33 The quagmire of trade-offs underlying the threat of limited air strikes for coercive purposes leads to ethical complications, particularly regarding the principles of right intention, likelihood of success, and risk of escalation. Most notably, these reputational costs can undermine the principle of right intention if leaders follow through on their threats out of concern for their personal reputations (decidedly not a right intention). Even more so, the use of limited air strikes for coercive purposes highlights nuances underlying the principles of likelihood of success and probability of escalation that need to be further addressed by theorists.
Policymakers often threaten or use limited air strikes under conditions that would meet the criteria for right intention. As Brunstetter and Braun explain, “Right intention for jus ad vim means quelling a specific threat, while causing the least amount of damage possible by protecting civilians,” and such acts “can serve to cripple those seeking to undermine peace and the status quo or to threaten the innocent.”Footnote 34 Accordingly, the threat or use of limited air strikes to prevent further acts of aggression or to protect civilians from further harm would conceivably pass the test of right intention. However, when such coercive threats fail, the principle of right intention can be undermined if policymakers enact limited air strikes to protect their reputations for resolve or out of concern for their personal prestige.
While protecting one's reputation may help stave off future harm to his or her own public and military, it does not directly address the immediate goal of rectifying injury in a given crisis. Furthermore, egoistic concerns over one's own prestige are not justifiable under the principle of right intention. Even more so, it could be argued that the desire to look tough for either domestic or international audiences does not meet the standard of right intention, as it is not focused on directly preventing harm.Footnote 35 The problem, however, is that a policymaker's actual motivations “can be difficult to discern,”Footnote 36 such as with Trump's actions in Iran and Macron's actions in Syria. Further complicating matters is the fact that policymakers may be driven by mixed intentions, such as having a desire to look tough while also having a desire to prevent future harm, or policymakers disingenuously claiming to be acting with the right intention when they are not. Clearly, however, the wrong intention would be threatening or employing a limited strike out of revenge.
The principle of likelihood of success is complicated by the difficulty of defining success in the context of coercion. As Reichberg and Syse explain, when applying this principle to coercive threats, “the question here would be whether the probability that a threat will successfully deter a behavior, thereby obviating the need to use force, will affect whether the threat can be ethically justified.”Footnote 37 A threat that is unlikely to deter or compel the target is difficult to justify under the principle of likelihood of success, even if it meets other criteria such as right intention, just cause, and proportionality. This all still begs the question of what constitutes success in a coercive episode. One cannot use the standard of victory, as it is difficult to conceptualize this outside of the context of war. Alternatively, one could consider whether political or military gains are made, but the question then becomes whether those gains are large enough to justify the use of limited air strikes.Footnote 38 In the case of the Soleimani strike, the Trump administration was successful in achieving its direct military goal. However, the strike neither deterred Iran from future aggression toward the United States and its allies nor compelled Iran to alter its behavior in the region. And Trump's failure to react decisively to Iran's subsequent reprisal further undermined the administration's credibility and reputation for resolve.
It can also often be difficult to determine whether the coercer has actually been successful in deterring or compelling the target. For example, there has been intense debate over whether Trump's strikes against Syria have been successful in coercing President Bashar Al-Assad.Footnote 39 While some argue that the strikes compelled Assad to alter his behavior, others point to the need to repeatedly use coercive limited air strikes across multiple years as evidence of their ineffectiveness. This being said, there are clear instances of coercive failure, such as Obama's red line against Syria. And limited military action more generally has a poor track record of achieving broader coercive goals.Footnote 40 Thus, one could argue that broadly speaking, limited air strikes are difficult to justify for coercive purposes under the principle of likelihood of success.
In addition, the threat and use of limited air strikes may also increase the risk of crisis escalation. This further undermines the principle of likelihood of success and creates additional complications for the principles of last resort and proportionality. Furthermore, this directly violates the jus ad vim probability of escalation principle.Footnote 41 When issuing coercive threats, policymakers have an ethical obligation to “try to avoid slipping into a fully-fledged war.”Footnote 42 And they need to “think about the possibilities of escalation before using [limited force]—not once force has already been employed.”Footnote 43 Yet, if a threat is unlikely to clearly achieve its stated coercive aims and instead increases the “probability that military means will have to be used,” followed by the intent to escalate to show resolve, it may be difficult to justify under this principle.Footnote 44 Thus, when evaluating the ethical implications of limited air strikes, it is important to consider whether policymakers have carefully assessed the risk of escalation. One could argue that even threats of limited strikes, if they are intended to demonstrate resolve, cannot be justified for coercive purposes because they carry with them the intent to escalate a conflict.
Conclusion
Limited air strikes are a poor coercive tool and are likely to increase the risk of escalation. The broader problem is that leaders often threaten to employ limited air strikes for lack of a better option because they believe they are a good middle-ground approach, or because they assume such actions will not lead to escalation. As a result, leaders may fail to carefully weigh the likelihood that the target will escalate the situation, or that the failure of the target to acquiesce to coercive demands may mean that the coercer needs to escalate the conflict in order to signal their resolve. This does not mean that policymakers should avoid issuing threats of limited air strikes altogether. It does indicate, however, that policymakers need to reconsider how they view and use threats of limited air strikes as a coercive tool to achieve broader strategic and political aims.
