Deterrence is using the threat of violence or denial to prevent certain actions from being carried out by the opposition (Lonsdale, 2008). Deterrence can be described as an act of prevention. It is similar to defence, but relies on military force to have a psychological effect on the enemy, as opposed to physical actions. One method of using deterrence is through punishment; whereby the enemy is convinced that attacking will cause losses that are so high that is not worth the possible rewards to be gained (Naroll, Bullough, & Naroll, 1974). The other method of deterrence is through denial; convincing the adversary that their plans are impossible to successfully achieve. These methods can be achieved by displaying superior military forces through numbers, technological advancements, fortifications, alliances with other powerful nations, and past military victories; all displaying national military prestige. Whatever its form, deterrence is to prevent an adversary from making aggressive actions.Actions aimed at deterrence were seen frequently during the Cold War. The Cuban Missile Crisis in 1962, three different nations could be seen attempting to use methods of deterrence using nuclear weapons. The US had recently installed nuclear missiles in Europe, aimed at the Soviet Union in an attempt to deter them from invading Western Europe. In response, the Soviets began installing missiles in Cuba, attempting to deter the US in turn. The third nation, Cuba, was interested in arming itself with nuclear weapons to deter the United States from invading again, as they had in 1961. The forth action of deterrence was made by the US as they deployed a naval quarantine around Cuba, threatening approaching Soviet ships to prevent further missiles from arriving (Franklin, 1997). This event is interesting because it not only displays multiple nations using deterrence methods to prevent each other from making certain actions, but it also displays many of the challenges faced by modern nations using deterrence, such as a lack of commitment to follow through with the threats and the adversary not reacting in the desired way.
Compellence is similar to deterrence, using psychological effects to convince the opponent to behave in a particular way and take particular actions. This is achieved through causing harm, or at least the intimidation of it (Lonsdale, 2008). This is often shown with the physical display of violence and capability. The display is more of a demonstration using a limited amount of the power available, rather than full scale war. This harm does not necessarily have to be only physical violence, but can be achieved through economics as well. Economic strikes are often used by the United Nations and the US by putting trade sanctions on nations that they are trying to influence, without turning to physical violence. These actions are used to try to compel the adversary into behaving in a particular way.
After WWII, the Soviet Union could be seen using compellence to spread communism and their sphere of influence. The countries in Eastern Europe such as Poland, Hungary, and Bulgaria quickly came under heavy pressure by the military might of the Red Army to adopt communism and join an alliance with the Soviets under the Warsaw Pact (Markey, 2018). These smaller countries were in no position to resist the threat of harm from the Soviets, especially after WWII, so they were easily compelled into acting how the Soviets wanted them to. This is an aggressive example, particularly from a western-bias point of view, but the use of compellence by world super powers to create large alliances is not uncommon. The formation of NATO by the western capitalist nations can also be used as an example, as the greater powers such as the United States and Great Britain compel smaller countries such as Belgium into joining with them. Strong countries often use their military power to compel smaller nations into alliances to strengthen their influence in the world.
Deterrence and compellence are not without their challenges. There are three factors that are required to make deterrence and compellence successful; capability, commitment, and communication (Lonsdale, 2008). Without one of these three factors, succeeding becomes far more challenging. Lacking in capability has an obvious result; if a state lacks the power and ability to intimidate, deny or inflict significant pain, then their ability to influence their adversary is significantly reduced. A lack of commitment is a common challenge faced in the modern and Cold War periods. This is due to the development of weapons of mass destruction. Few nations wish to use these weapons because of their pure destructive capability and their potential for the destruction of the human race. The challenge then arises when trying to convince an adversary that you are prepared to use them to achieve your goals and getting taken seriously, as seen in both the Cold War with the Soviets and US, and into modern conflicts such as the US attempting to denuclearise North Korea. Finally, communication with the enemy is a challenge that, if not overcome, makes attempting to deter or compel pointless. This is because without clear communication the adversary will not be aware of the nation’s forces, ability, or intent; all factors will be invisible, making the threat unknown. These three factors for success are the first challenges to be overcome for compellence or deterrence to be accomplished.
Having the ability, the commitment, and having the threats communicated to the enemy are not the end of the difficulties that can be faced. Depending on the adversary, the result of an attempt to deter or compel them can result in different outcomes than what was desired. According to Lawrence Freedman (as cited in Lonsdale, 2008), “deterrence works best when the targets are able to act rationally.” The inverse of this is proven in the examples of modern states attempting to deter terrorists groups that have formed in recent years such as al Qaeda and the Islamic State. Many members of these organisations are considered zealots all too willing to die for their cause. These people are often immune to psychological threats, which make compelling and deterring them a challenge and arguably non effective.
A target who behaves rationally will be affected by deterrence and compellence actions, but not necessarily in the desired way. When threatened, an adversary could feel like it is backed into a corner, therefore forced to respond in a violent or aggressive manner. This does not have to be a physical attack; the response can instead be the beginning of an arms race (Naroll et al., 1974). This arms race develops as each side improves both the size and technologies used by their militaries in order to not fall behind and be at the mercy of the other. This could be seen during the first decades of the nuclear age as the Soviet Union and United States dramatically increased the sizes of their nuclear arsenals in an attempt to have a psychological effect on each other. When trying to manipulate an adversary through psychological means, the risk of having them react by increasing their strength is a further difficulty to be faced by the use of deterrence and compellence.
Nations seek to use compellence and deterrence instead of more physically violent actions for a multitude of reasons. Military theorist Sun Tzu (n.d.) stated that “to fight and conquer in all your battles is not supreme excellence: supreme excellence consists in breaking the enemy’s resistance without fighting” (p. 28). This breaking of resistance without having physical conflict is what using deterring or compelling methods hope to achieve. This is preferred because conflict is costly in both lives and resources, and as a consequence, is often unpopular with the population. Conflict is particularly unpopular in modern day culture, as recent wars such as the Vietnam War demonstrated. This war cost numerous American and Vietnamese lives, as well being morally questionable whether it should have occurred, and is still fresh in the minds of the populace (Hanson, 2007). Governments cannot act without support of their citizens, so seek to use compellence and deterrence to achieve their goals instead of the more violent, costly and unpopular forms of military use.
Compellence and deterrence are two uses of military forces. They are aimed at using a psychological effect, rather than more physical approaches, to achieve goals. The Cuban Missile Crisis is a good example of deterrence and its challenges, while the development of alliances during the Cold War displays larger nations compelling smaller ones. These methods come with challenges such as the requirement for capability, commitment and communication, as well as the risk of an unintended response. In modern times nations have preferred to use these methods rather than more aggressive means, as physical war is both costly and unpopular. Compellence and deterrence can be an effective way for nations to achieve their goals.