Trump Can’t Have His Deterrence Cake and Eat It Too
In the wake of Donald Trump’s tomahawk missile strike against Syria, pundits and policy observers have been quick to crow about the deterrent value of such strikes. Even Vice President Mike Pence couldn’t pass up the opportunity to comment while on an official visit to East Asia, noting that “the world witnessed the strength and resolve of our new president in actions taken in Syria.” Some, including the president and the Department of Defense, have trumpeted their immediate deterrent value in preventing further chemical weapons attacks. Others have argued that there is a larger deterrent benefit vis-à-vis other potential adversaries such as North Korea, Russia, and China. Importantly, not only are both sides of this debate wrong insofar as the United States won’t garner much deterrence benefit from recent actions, but they cannot also be right at the same time. In other words, the better that Trump’s actions in Syria are at strengthening immediate deterrence—that is, they mitigate a pressing short-term threat in the midst of a crisis such as another usage of chemical weapons—the worse they are at bolstering general deterrence, which aims to prevent other adversaries from taking provocative moves that would ensnare the United States in crises to begin with.
Understanding that Trump can’t have his deterrence cake and eat it too is paramount given that his administration seems to be increasingly enamored with the deterrent value of displays of military force. For instance, he recently authorized the use of the “Mother of All Bombs” (MOAB) against the Islamic State in Iraq and Syria (ISIS) targets in Afghanistan. His administration also claimed to have dispatched a carrier strike group to monitor a potential North Korean nuclear test before later backtracking. Should the Trump administration and the Washington, D.C. foreign policy establishment continue to misinterpret the deterrent benefits of such military actions, then not only will the United States waste valuable resources on useless and ineffective operations, but they will increase the probability of being pulled into truly dangerous crisis situations and erode, rather than bolster, their deterrent posture.
Military actions have two primary benefits. First, there is the value garnered by successfully accomplishing the mission objective. Second, there is deterrent value, which relates to how military actions shift an adversary’s cost-benefit calculations about future actions against the United States. Given that Trump’s recent military actions had little to no objective military value, it is unsurprising that his boosters would latch onto their deterrent value to post hoc justify their necessity. Unfortunately for Trump supporters, and foreign policy hawks more broadly, not only will Trump’s recent military escapades not provide much general or immediate deterrent benefit for the United States, but enjoying one of these benefits precludes enjoying the other.
The important distinction between general and immediate deterrence actions has been lost in the mad scramble by pundits and foreign policy observers to dust off Cold War-era theories of deterrence in an attempt to interpret and justify Trump’s actions. Shifting the calculus of an adversary who is considering an immediate aggressive action is profoundly different than influencing the more nebulous calculations of an adversary contemplating the possibility of aggression in the future. For instance, the balance of capabilities between two opposing sides in a crisis will have no independent impact on the outcome of the crisis because such observable factors are often known in advance and thus already taken into consideration in the decision to enter the crisis in the first place. Thus, what matters in immediate deterrence scenarios is the ability to credibly signal resolve and private information about capabilities that might not have been known in advance.
Will the Trump administration garner benefits for immediate deterrence through its recent actions in Syria? Setting aside the motivated rhetoric of Trump supporters eager for a foreign policy “win” to bolster their plummeting domestic political agenda, the objective odds of such a benefit are low. As noted above, the balance of capabilities is irrelevant in immediate deterrence situations, meaning a state will prevail if they can signal that they have a fundamental interest in the matter at hand, and are resolved to accept costs to preserve those interests. Trump’s protestations to the contrary, the United States has little to no strategic interests in Syria. Moreover, although upholding the international norm against the use of chemical weapons might be desirable, it comes nowhere close to a core security interest. Furthermore, in terms of resolve, even if Trump and his administration see greater U.S. interests in the Syrian conflict than the Obama administration did and are resolved to protect those interests, his pinprick strike cannot be interpreted in a vacuum given roughly six years of U.S. non-involvement in the conflict. Trump’s strike was not a costly signal of resolve and came on the heels of Obama-era inaction. Thus, if Assad and Syria updated their estimates of U.S. interests and resolve over their use of chemical weapons, it is likely they only slightly did so.
What about general deterrent benefits? Here the connection between Trump’s specific actions and future adversary actions become even more tenuous. Although not without its flaws, research by Daryl Press of Dartmouth College has convincingly demonstrated that decision-makers discount the past actions of a particular country in assessing their future credibility. For past actions to have an impact on assessments of future action, they must provide some interpretable symbol of a country’s capabilities, interests, or resolve. These signals will be more credible when there are clear connections between the circumstances of past actions and future actions, for instance when the interests are similar. If the interest that the United States was trying to signal in attacking Assad was preventing chemical weapons attacks, then it is hard to see how this interest is transferable to relations between the United States and other potential adversaries, such as Russia or China. Thus, there will be few general benefits for deterring other adversaries from U.S. actions in Syria.
Perhaps recognizing this difficulty, supporters of Trump’s strike have argued that in fact Trump wasn’t trying to send a clear signal of interests and resolve. Rather, in line with Thomas Schelling’s oft-quoted aphorism that “it does not always help to be, or to be believed to be, fully rational, cool-headed, and in control of oneself or of one’s country,” observers have argued that Trump may be attempting to appear irrational to gain a bargaining advantage à la Richard Nixon’s “madman” theory.
There are manifold flaws with this argument. First, there is the possibility Trump is not rationally irrational but actually irrational, and therefore cannot calculate the risks of his actions. Second, it is unclear whether making opponents uncertain about your interests, resolve, and thus response to their actions really gives you a bargaining advantage. Increasing the uncertainty around the costs you are willing to bear given a particular demand may deter some adversaries, but it could incentivize others to roll the dice and hope that fortune is on their side. Third, it is impossible to fully control how a potential adversary interprets a signal, and the murkier the signal, the less control a state has. Whatever Trump’s goals, therefore, he is less likely to achieve them since adversaries won’t know what they are and therefore will be unable to construct a bargain that comes close to them.
Finally, even if there are immediate or general deterrent benefits from Trump’s actions, those benefits are mutually exclusive. The more narrowly targeted a deterrent threat is, the less it is a signal of broader resolve. If a country’s resolve in a crisis is due in some part to its interests in that crisis, then signals of resolve will only carry over to situations where there are equal or greater interests at stake. Trump and his foreign policy decision-makers may thus be betting that reacting strongly to a situation in which the U.S. has little stake will thus make all other threats credible. This logic, however, is flawed. Trump’s Syria strike can also be easily written off as the one-off firing of an unpredictable actor, meaning that unless Trump proves his high level of resolve through repeated responses to low-level actions, such bluster would not appear credible. Given sagging approval numbers at home, however, such a sustained effort may prove an even riskier move domestically than it is internationally.