Traditional nuclear deterrence strategy holds that there are two differing strategic approaches on deterrence, offensive and defensive. This is increasingly prescient as the doomsday clock has once again approached ‘one minute to Midnight’. Herein, a brief consideration of these two branching strategies vis-à-vis game theory analysis shall be undertaken.
This game theory approach can highlight the successes and failings of these differing strategies, and the axioms which must be assured in order for their coherence to remain and their pertinence to be assured. Two different branches of deterrence theory can be distinguished; (a) offensive deterrence, a retaliatory capacity against aggression, and (b) defensive deterrence, a credible missile shield. When each of these two branches of strategy are analysed through the use of Game Theory, we achieve an analysis which can be used to highlight either, or both, achieve successfully their aim of acting as a deterrent.
First, our attentions shall be turned to the traditional Unilateral Deterrence Game, which refers to the condition of an independent deterrence capacity, vis-à-vis an aggressor country.
| Defender
Challenger |
Hold | Aggress |
| Hold | Status Quo | N/A |
| Aggress | Defender Concedes (Deterrence Failure) | Retaliation
(Deterrence Failure) |
Table 1.
Table 1 shows the Unilateral Deterrence Game of one defender country vis-à-vis an aggressor (challenger) country under the condition of perfect information.
We can focus initially upon this game within the concept of offensive deterrence (a). We can see from this matrix that there are three different outcomes to the game, as the defending party in this game cannot attack pre-emptively. The outcomes are Status Quo, Defender Capitulating, or a Retaliative Strike. If we consider the “utilities” or points attached to each action there is an insight to be gleaned into the equilibrium of the model, and an explanation of the nature if the deterrence[1], the utilities attached are demonstrative rather then scientific. The utility at Status Quo is (0,0); as neither side has made a gain or loss. The utility at Defender Concedes would be around (1,-2), depending on the specificities, which would highlight the utility gained for the aggressor for meeting their objectives and the loss incurred by the defender, from an invasion and loss of liberty to a unmatched nuclear strike. The Utility at retaliation would be around (-2,-2), which shows that the aggressive deterrence capacity has been used to offset the potential losses occurred to the defender following classic deterrence theory; at this node both parties are losers. This model for Offensive Deterrence Strategy in a two player game under perfect information shows therefore that the interest of a defender retaining a credible retaliatory capacity is that, when the utilities of the different outcomes are considered, the Pareto equilibrium is at the node Status Quo: a rational actor would therefore not aggress this defender for fear of the loss of a greater value of utility then they would stand to gain.
Under Defensive Deterrence (b) the three possible scenarios remain the same under the conditions of perfect information. There are therefore still three possible conclusions; Status Quo, Defender Concedes, and Retaliation. The aim is not to change the game, but rather to shift the utility values attributed to the results for the two players. At Status Quo, and at Defender Concedes the utilities remain the same; using our example above (0,0) and (1,-2) specifically, nevertheless at the node ‘Retaliation’ the utilities would change. At retaliation, given that the nature of the deterrent is defensive rather than offensive the utility assigned to the defender would change, rather than the Utility for the aggressor; except to qualify failure in strategic objective. Depending on the effectiveness of the Defensive Deterrent the change within the range of (0,0) wherein the defensive deterrent has been completely effective and so no strategic gain has been made against the defender by the aggressor and the defender has equally sustained no damage in defence, up-to around (0.7,-1) wherein some utility has been gained by the aggressor through the success against some strategic targets and some damage has been sustained by the defender. Following this analysis, it shows that a completely defensive strategy towards deterrence is a losing strategy under the conditions of perfect information; there is no equilibrium gained because for the aggressor the most opportune strategy becomes to aggress as no loss of utility can be perceived.
This shows therefore the fundamentality of a credible threat to the aggressor by the defender in order to obtain the equilibrium of Status Quo and so protect her interests. Therefore a “tailored defense”[2], which combines elements of these two strategies, or at the least the credible potential for extended deterrence is necessary in order to guard the defender against aggression within the paradigm of a perfect information game.
We can nonetheless distinguish the presence of a Non-Perfect Information Game, which replicates real life situations better and explains the role of brinkmanship within deterrence strategy. This is Stephen L. Quackenbush’s key contribution to deterrence theory within game theory analysis[3].
The Non-Perfect Information Game demonstrates the changing equilibria based upon the two axes Pdef for the defender and PCh for the aggressor which demonstrate on both axes the conditions of perfect information on a scale from 0 to 1. This matrix shows, under the differing conditions of imperfect information, the equilibria change, and the element of bluffing herein, uncertainty can gain a greater importance in deterrence strategy within this context. In the context of nuclear deterrence, this is of limited interest; as it is in the defenders interest to provide near-perfect information of their capability, through nuclear and missile testing to potential aggressors, this would prove that it has an offensive deterrence capability, creating a Pareto equilibrium between aggressor and defender at Status Quo. Nevertheless, in terms of traditional deterrence, the aim of avoiding being aggressed this is of interest. It is equally of interest when weak nuclear powers are considered, who instrumentalise such arms to political objectives.
This is due to the key insight that the ‘separating equilibria’ or in other terms uncertainty and the bluff equilibria can be attributed with being the most likely Pareto equilibrium within an imperfect information deterrence game. This indicates the condition of instability based upon such a model. Given such a large margin for outright bluffing, or otherwise uncertainty over actions, the non-strategic but rather political process of negotiation comes to the fore. This indicates therefore that effective deterrence is not obtained under such a model, only the insecurity which creates room for negotiation and a political solution to any potential conflict.
Following from such a consideration and analysis of Game Theory, it is clear that the only effective method of deterrence is within the paradigm of an offensive deterrence capability which is subject to the conditions of perfect or near-perfect information. It is therefore in the interests of the defender to ‘publicise’ as loudly as possible their credible nuclear deterrence through the use of nuclear and missile testing.
Case Study: Trident as an effective independent nuclear deterrent?
Trident came into force as the UK nuclear deterrent the 15th July 1980[5], replacing the Polaris system emanating from the 1963 Polaris sales agreement. One commonality between both of these systems is the fact that the ballistic missiles, which are the component officially bearing the name Trident, are sourced from the United States, equipped to UK submarines and equipped with UK built nuclear missiles[6]. Whilst the UK holds operational independence and sovereignty over the Trident deterrence system, the UK government nonetheless commits its nuclear deterrence capacity to the NATO alliance and their Nuclear Planning Group wherein this does not conflict with UK vital interests[7].
This Trident deterrent can pose two questions therefore, pertinent above all at the moment due to the great present debate concerning the system’s renewal. Is Trident effective? Is Trident independent?
For a deterrent to be effective, its menace and credibility must be sufficient to dissuade any power from aggressing in order to advance their own strategic interests and so repulse the idea of aggression as a valid strategy against the defender, in this instance the UK. In terms of menace, the Trident system has a certain cardinal destructivity, at any moment one submarine from the fleet of 4, armed with 48 Nuclear Warheads aboard 16 missiles at around 100 Kilotons per Warhead, is deployed[8]. This assures that the menace assured by Trident is sufficient in order create a sufficiently great negative utility to any aggressor to dissuade attack through the fear of retaliation. Trident’s level of credibility is derived from the fact that, on a technical level, the number of warheads is considered sufficient to pierce any missile shield and so inflict serious damage on the aggressor[9], and on a strategic level by the fact that the decision to retaliate or not is taken in advance by the Prime Minister and placed in a letter on the submarines in the event that retaliation should be necessary. The chain of command is therefore impervious to any first strike, as all necessary information and systems for a second strike is in place on the submarines[10]. This nonetheless necessitates that the incumbent Prime Minister seems to be prepared to use retaliation, whether they are a ‘Hard’ or a ‘Soft’ defender in the argot of Game Theory. This is of debate with some former Prime Ministers and certainly within the current political spectrum in UK politics; credibility of the Trident system is therefore dependent upon the credibility of the Head of Government to be prepared to retaliate.
In terms of Independence, there is the constraining element to the UK deterrent; which is the investment of UK nuclear capability towards the NATO alliance[11]. This constriction of independence towards participation with the Nuclear Planning Group within the NATO formation extends the use of the UK deterrent towards the ends of extended deterrence within the European continent providing NATO extended deterrence in this sphere greater credibility when considered vis-à-vis the prospect of solely American extended deterrence which could be of a potentially limited, and therefore dubious, interest to US vital interests. The UK deterrence, in the sense that it equally provides a type of European extended deterrence cannot be said to be ‘independent’ in the sense of being insular to the world. Equally, there is the issue of technical dependence; the ballistic missiles, bought from the US, when non-operational are housed in the US Strategic Weapons Facility in Kings’ Bay, Georgia where they also undergo maintenance[12]. There is therefore an issue of being reliant on US cooperation for the continued operational ability of the Trident deterrent, which is acceptable when considered in the prism of being deployed principally within the context of the NATO extended deterrence program in Europe, as the aims of the UK deterrent and a NATO deterrent would therefore become indivisible. The UK nevertheless guards the proviso of using independently the deterrence capacity in the event of retaliation against an attack to UK vital interests in any scenario which may entrain this without becoming a NATO defence based issue[13]. The Trident deterrence program is therefore effective as a deterrent, if the Head of Government is seen as a ‘Hard Defender’, and independent without being insular like the French deterrent, preferring to remain engaged and be employed in close co-ordination with the NATO alliance. This gives the UK an enhanced influence within the NATO alliance, and particularly in the Nuclear Planning Group vis-à-vis European extended deterrence; showing a fundamentally political sub-motive to this type of deterrence strategy.
[1] Stephen L. Quackenbush. Understanding General Deterrence: Theory and Application. Palgrave Macmillan. 2011.
[2] “Deterrence: Its Past and Future Panel Two” Han-Sung Joo, President Korea University Nuclear Drawdown, Deterrence, and Non-Proliferation. Question 4. http://www.nuclearsecurityproject.org/publications/deterrence-its-past-and-future-panel-two Retrieved 02/12/2015.
[3] Stephen L. Quackenbush. Understanding General Deterrence: Theory and Application. Palgrave Macmillan. 2011.
[4] Stephen L. Quackenbush. Understanding General Deterrence: Theory and Application. Figure 3.1, pg 45. Palgrave Macmillan. 2011.
[5] The Future United Kingdom Nuclear Deterrence Force. Ministry of Defence. July 1980. Defence Open Government Document 80/23. Francis Pym.
[6] Ibid.
[7] Ibid.
[8] House of Commons Select Committee of Defence. The Eighth Report: 2. The UK’s Strategic Nuclear Deterrent. 2005/06. http://www.publications.parliament.uk/pa/cm200506/cmselect/cmdfence/986/98605.htm Retrieved 02/12/2015.
[9] The Future United Kingdom Nuclear Deterrence Force. Ministry of Defence. July 1980. Defence Open Government Document 80/23. Francis Pym.
[10] A guide to Trident and the debate about its replacement. 30th September 2015. BBC. http://www.bbc.com/news/uk-politics-13442735 Retrieved 02/12/2015
[11] The Future United Kingdom Nuclear Deterrence Force. Ministry of Defence. July 1980. Defence Open Government Document 80/23. Francis Pym.
[12] House of Commons Select Committee of Defence. The Eighth Report: 2. The UK’s Strategic Nuclear Deterrent. 2005/06. http://www.publications.parliament.uk/pa/cm200506/cmselect/cmdfence/986/98605.htm Retrieved 02/12/2015.
[13] The Future United Kingdom Nuclear Deterrence Force. Ministry of Defence. July 1980. Defence Open Government Document 80/23. Francis Pym
desai. 