DEFENSE, DETERRENCE, AND COMPELLENCE: THREATS, PROMISES, AND CREDIBILITY

DEFENSE, DETERRENCE, AND COMPELLENCE:THREATS, PROMISES, AND CREDIBILITY Topics # 14-16

Defense and Deterrence • Consider two actors with opposed interests regarding some “prize”: • A: Aggressor (who wants to change the status quo) • D: Defender/Deterrer (who wants to maintain the status quo) • A has two choices: • to attack D, using offensive capability to seize the “prize” (e.g., territory ) belonging to D, or • to refrain from attacking A. • If attacked, D has two choices: • to (try to) defend against the attack, or • to give in. • In this highly oversimplified world, there is some balance between A’s offensive capability and D’s defensive capability which determines the payoffs in the event of a conflict. • Since the players make sequential choices with perfect information, it is best to represent the game in extensive form.

Defense and Deterrence: Scenario 1 • Suppose that • the prize is worth 10 (“units of payoff”) to both A and D, • D has an effective defense against A, • i.e., D can prevent A from seizing the prize, and • the cost of fighting is 5 to both A and D. • Since D’s defense is effective and the cost (to D) of fighting is less than the value of the prize (to D), • D’s dominant strategy is to defend if attacked, so • when A “looks ahead and reasons back,” • A chooses to refrain from attacking, • that is, A is deterred from attacking in the first place. Note: the payoffs are (A,D)

Defense and Deterrence: Scenario 1 (cont.) • We see that an effective defense is also a highly effective deterrent. • Note also that D does not need to make an explicit deterrent threat, • since D is just “threatening” to do what it makes sense for D to do anyway. • Such a threat is commonly called a warning. • An expensive defense system against a rational opponent A may be highly valuable to D even (or especially) if it is never used. • In contrast, there may be reason to regret building expensive defenses against “attacks” by nature (e.g., floods, hurricanes, earthquakes, etc.) in the event they are never used. • Such defenses do not affect the likelihood that natural “attacks” occur.

Defense and Deterrence: Scenario 2 • Now suppose • the costs of fighting remain the same to both A and D, but • D’s defense is ineffective, i.e., • D cannot prevent A from seizing the prize. • Since D’s defense is ineffective, • D’s dominant strategy is to give in if attacked, so • when A “looks ahead and reasons back,” • A chooses to attack. • Indeed, attacking is A’s dominantstrategy, since A gains even if D mounts a (futile) defense. • However, the next scenario shows that an ineffective defense may still be a successful deterrent.

Defense and Deterrence: Scenario 3 • Now suppose that the cost of fighting is 15 for both A and D • and thereby exceed the value of the prize, • but D’s defense remains ineffective. • Because D’s defense is ineffective, • D’s dominant strategy is to give in if attacked, so • when A “looks ahead and reasons back” • A chooses to attack. • However, attacking is no longer a dominant strategy for A, because • A is counting on “rational” D not mounting a futile defense. • Unlike Scenario 2, A will not attack if A expects D to defend.

Defense and Deterrence: Scenario 3 (cont.) • So if D can make a credible commitment to defend if attacked, • even though the defense is ineffective • A may be deterred from attacking, • because the cost of fighting (to A) exceeds the value of the prize (to A). • Such a credible commitment requires an explicit deterrent threat. • And the nature of D’s threat is to say, “if you attack, I will do something it does make sense for me to do.” • So this is not merely a warning, • and it is inherently difficult to make the threat credible.

Defense and Deterrence: Scenario 3 (cont.) • While there is no question that D has the capability to carry out this threat, • there is considerable question whether D would actually carry out the threat if attacked, • because D will pay the cost of fighting and still lose the prize. • In light of the discussion on Bargaining Tactics, • D might try to “tripwire” its defense, etc.

Defense and Deterrence: Scenario 4 • Finally suppose that the cost of fighting is for 15 for both A and D, • but D’s defense is once again effective. • Even though D’s defense is effective, • D’s dominant strategy is still to give in if attacked, • because the cost of fighting (to D) exceeds the value of the prize (to D), so • when A “looks ahead and reasons back” • A chooses to attack. • But once again attacking is not a dominant strategy for A. • But if D can make a credible commitment to defend if attacked, • A is once again deterred from attacking, • because the cost of fighting (to A) exceeds the value of the prize (to A).

Defense and Deterrence: Scenario 4 (cont.) • Such a credible commitment requires an explicit deterrent threat. • Once again while there is no question that D has the capability to carry out the deterrent threat, • there is considerable question whether D will choose to carry out the threat if attacked, • because the cost of fighting exceeds the value of the prize. • Note that the payoffs to the players are symmetric in Scenario 4 (unlike 3), so D is in a somewhat more favorable bargaining position in Scenario 4 than 3.

General Observations • D may be “the bad guys” (e.g., hostage holders, deterring an “attack” by authorities). • A may be “the good guys” (e.g., police trying to free the hostages). • Note that in the preceding scenarios, no fighting actually occurs, • except possibly in Scenarios 3 and 4, if D actually carries out a deterrent threat that (evidently) was not credible to A. • In the real world, • A and D may misperceive the payoffs as evaluated by the other party; and • the costs of fighting are not fixed because if fighting starts an endurance contest between A and D may result • Remember the Dollar Auction Game in Topic #2, • in which both sides may pay costs of fighting that (greatly) exceed the value of the prize.

General Observations (cont.) • An even more important consideration is that the immediate conflict may be embedded in a larger ongoing conflict in which reputation effects are important, • which thereby changes the payoffs to the players, • as reputations are at stake (perhaps especially for D) in addition to the value of the prize. • Remember that in Scenarios 3 and 4, D’s deterrent threat was to use an ultimately ineffective defense that would impose high costs on A (as well as D).

Deterrent Threats: Pure Punishment • But D can make deterrent threats based on the capability to destroy anything that A values. • As Schelling notes, it is usually much easier and cheaper (especially in the modern world) to destroy things than to create (or defend) them. • In a few hours, the 9/11 terrorists • destroyed things worth about $100 billion (and years to contruct) at a cost of about $100,000 (? ) • and took about 3,000 lives at a cost of 19 lives. • What was unusual is that this action was neither • an attempt to destroy military capability (like the attack on Pearl Harbor), nor • fulfillment of a specific deterrent (or compellent) threat. • Of course, nuclear weapons hugely enhance the capacity to destroy. • Moreover, bombers and missiles allow D to destroy things of great value to A without D first defeating and destroying B’s military capability, • and may allow A to inflict similar damage in retaliation, • so the destruction may be mutual.

Deterrence: Threats to Punish (cont.) • It is important to note the concept and reality of deterrence are not restricted • to nuclear weapons (“nuclear deterrence”), • nor even to military capabilities. • Another arena of social interaction in which the language of deterrence is commonly used is the criminal justice system, • where its applicability is not limited to murder and the death penalty only.

Conditions for Successful Deterrence • These appear to be the conditions for successful deterrence: • D must be able to detect the attack or other action against which the deterrent threat is aimed. • This is not problematic in deterring military attacks (least of all a nuclear attack) • But it is problematic in • deterring criminal and other socially harmful acts, and • deterring violations of arms control and similar international agreements. • D must have a visible and adequate capacity to carry out the threat, • and retain this capacity even if A actually attacks, • that is, A must not be able to carry out a pre-emptive attack that deprives D of the capacity to punish.

Conditions for Successful Deterrence (cont.) • D must be perceived by A to be • willing to carry out the deterrent threat or • otherwise committed to carrying it out. • A must make rational calculations about whether to attack or refrain from attacking. • The willingness of D to carry out the deterrent threat is usually the most uncertain condition, because • carrying out the threat does not (usually) protect or regain the prize, and • and the punitive consequences are (usually) visited on D as well as A. • In principle, all that matters is A’s perception of all these conditions. • Deterrence can succeed even if D is bluffing with respect to the first three conditions, • but D’s actual capabilities and intentions most reliably shape A’s perceptions.

Coercion and Compellence • Let’s reconsider Scenario 1, in which D has an effective defense and the cost of fighting is less than the value of the prize. • Remember that D’s effective defense was also a successful deterrent to a possible attack by A. • However, if A has the capability to impose punishment (beyond the costs of fighting) on D greater than the value of the prize, • A may be able to coerce D into giving up the prize as a result of a compellent threat, i.e., • A can threaten to punish D (almost certainly at some cost to A also) to an extent that exceeds the value of the prize (to D) in event D does not give up the prize.

Coercion and Compellence (cont.) • Given the extensive form to the right, if A just looks ahead and reasons back, A refrains from attacking or coercing. • However, if A can somehow credibly commit to choosing “Punish” at the final move, • A can anticipate that that D will “Give In” rather than “Resist” at the previous move, and therefore • A can win the prize by means of the compellent threat.

Types of Credible Commitments • Consider a sequential choice game with perfect information in which each player makes one move. • Let’s label the choices each player has simply Left and Right • In the absence of any communication, P1 looks ahead a reasons back. • If credible commitment by P2 is possible, what sorts of commitments may P2 make that may improve the outcome for P2? • Such a commitments makes a difference only if it commits P2 to a choice that P2 would not otherwise make. • P2 may make • an unconditional commitment (to choose Left or to choose Right), or • a conditional commitment (e.g., if you choose Left, I’ll chose Right)

Unconditional Commitment • In this game, if P1 looks ahead and reasons back, the outcome is (R,L) = (+2,-2). • But if P2 commits to choose R no matter what, and if this commitment is credible to P1, P1 will change his choice to L and the outcome will be (L,R) = (-2,+2). • Note that this game is Chicken, where • L = swerve, and • R = straight. • In absence of P2’s commitment, P1 has a first-mover advantage, which P2 tries to deprive P1 of by a pre-emptive commitment to R. • Note that P2’s commitment, if credible, will not actually be tested. Note: payoffs are (P1,P2)

Conditional Commitment: The Threat • In this game, if P1 looks ahead and reasons backs, the outcome is (R,L) = (+2,-2). • But if P2 commits (threatens) to choose R in the event P1 chooses R, and if this threat is credible to P1, P1 will change his choice to L and the outcome will be (L,L)= (-2,+2). • In this simplified game, this may be regarded as either: • a deterrent threat (P1 must not choose R), or • a compellent threat (P1 must choose L). • Note that P2’s threat, if credible, will not actually be tested, • So nobody (not even P2) knows for sure whether P2 would have carried out the threat.

Conditional Commitment: The Promise • In this game, if P1 looks ahead and reasons backs, the outcome is (R,R) = (+2,+2). • But if P2 commits (promises) to choose L in the event that P1 chooses L, and if this promise is credible to P1, P1 will change his choice to L and, if P2 does not renege on his promise, the outcome will be (L,L) = (+3,+3), an improvement for both players. • Note that this game is the Prisoner’s Dilemma, where • L is “stay silent” and • R is “confess.” • Note that P2’s promise, if credible, will be tested, and P2 will have the opportunity to renege on the promise.

Conditional Commitment: Combined Threat and Promise • In this game, if P1 looks ahead and reasons backs, the outcome is (R,L) = (+2,-2). • If P1 wants to improve the outcome for himself by credible commit-ment, P1 must make both a threat and a promise, i.e., • if you choose R, I’ll choose R (to punish you), but • if you choose L, I’ll choose L also (and I won’t exploit you by choosing R). • If the combined threat and promise are credible, the outcome will be (L,L) = (+1, +2). • Note that P2’s threat, if credible, will not actually be tested, but P2’s promise will be tested, and P2 will have the opportunity to renege on the promise.

Credibility and Risk • In these example, we have assumed that commitments, including threats and promises, are either credible or not credible. • P1 might instead believe there is some quantitative probability p (less than 1 but greater than 0) that P2 will live up to his commitments. • We can then calculate the critical risk p* that will just suffice to deter (etc.) P1. • This critical risk will dependent of the cardinal/interval values of the relevant payoffs.

Deterrence and Compellence in a Hostage-Holding Game • Terrorists, criminals, etc., hold one or more hostages, and they want to • avoid capture by the authorities and/or • coerce the authorities into other concessions. • They are surrounded by police authorities. • The authorities want to free the hostages and capture the hostage-holders without making any substantial concessions to them. • The bargaining power of the hostage-holders lies entirely in the fact they hold the hostages and can harm/kill them. • If the authorities can somehow free the hostages, • or if the hostage-holders ever carry out their threat to kill the hostages, • the bargaining power of the hostage-holders evaporates and they can be readily captured.

Hostage-Holding Game (cont.) • The hostage-holders can use their bargaining power to support both a deterrent threat and a compellent threat. • The deterrent threat is: if you (authorities) try to free the hostages and/or capture us, we will kill the hostages before you can do so. • The compellent threat is: if you do not give in to our demands (for exit from the country, for release our comrades in prison, for ransom, etc), we will kill the hostages. • Carrying out either type of threat is a total defeat for the hostage-holders (and a substantial -- but not total -- defeat for the authorities), and therefore • their threats are not highly credible.

Deterrent vs. Compellent Threats • Adding to the tension, the authorities have a incentive to launch a pre-emptive attack to free the hostages and capture the hostage-holders, • Before the hostage-holder can carry out their threat, • and the hostage-holders know the authorities have this incentive • In such situations, • the deterrent threat is usually successful (at least for a while) while • the compellent threat usually fails. • There are several reasons why (in the real world) compellent threats are less likely to be successful than deterrent threats. • But these difference do not show up in simple game representations of conflict situations.

Deterrent vs. Compellent Threats (cont.) • With respect to the hostage-holders’ deterrent threat, • the authorities have the “last clear chance” to avoid mutual disaster • i.e., initiating a shoot-out that puts the hostages and others at risk, and • they almost always are willing to out-wait hostage-holders • unless the condition of the hostages becomes dire. • With respect to the hostage-holder’s compellent threat, • the problem for the hostage-holders is that they must set a deadline by which time authorities must comply with their demand, • so in this respect the hostage-holders have the “last clear chance” to avoid mutual disaster, • e.g., killing the hostages, and • they always will be tempted to extend the deadline, and • the authorities know this.

Deterrent vs. Compellent Threats (cont.) • There is a second reason why in general deterrence is more likely to succeed than compellence. • Real world games do not have complete information, in that • the players do know each other’s payoffs for sure • In fact, players may not know all of their their own preferences for sure. • This means it is often not clear whether deterrence is needed in the first place, e.g., • whether A will really attack D if A believes they can “get away with it.”

Deterrent Threats (cont.) • Therefore, in the real world successful deterrence is often “observationally equivalent” to unnecessary deterrence. • “May This House Be Safe from Tigers” story [NY Times Square] vs. • “May Western Europe Be Save from Russians” story [Fulda Gap] • This fact also suggests there may be a problem in main-taining political support for deterrence over the long term.

Deterrence vs. Compellence • Giving in to a deterrent threat • does not require any change in behavior by A and • may therefore be invisible and not costly in terms of A’s prestige and reputation. • “We were never planning to attack in the first place.” • On the other hand, giving in to a compellent threat • does require a change in behavior by the recipient of the threat and • is therefore highly visible and costly in terms of prestige and reputation. • (First) Gulf War: • Iraq-Kuwait pre-August 1990: US deterrence failure • Iraq-Kuwait post-August 1990: compellence failure (followed by US offensive success) • Korea pre/post June 1950 somewhat similar: • US/Western initial deterrence failure • Did China try to deter US/UN from crossing the 38th Parallel and “liberating” North Korea? • Or did it want a surprise offense to destroy US military capability and prestige?

Deterrent Threats (cont.) • There is another political problem in maintaining deterrent threats: • while successful deterrence is largely invisible (because it cannot be distinguished from unnecessary deterrence), • unsuccessful deterrence is highly visible. • The “Warden’s Survey” of death row inmates. • His sample is biased, including only deterrence failures. • The deterrence successes are all outside the prison • and therefore are not included in the survey • The deterrence successes outside the prison are mixed in with • a vastly larger number of cases of unnecessary deterrence, and • a some additional cases of deterrence failure.

Generalized Deterrence • Recall that any immediate conflict may be embedded in a larger ongoing conflict, • in which reputation effects are important, • which thereby changes the payoffs to the players, • as reputations are at stake in addition to the value of the prize. • This means that D may have an incentive to defend (or punish), even if doing so is more costly in the short run than giving in (and losing the prize). • Of course, A may likewise may have an incentive to commit aggression, even if doing so is more costly than refraining from attack (and not winning the prize). • Thus early contests of will take on unusual importance, • e.g., negotiations about the shape of the negotiating table.

Generalized Deterrence (cont.) • The value of the prize in early contests is not its intrinsic “strategic value” but its significance as a precedent and an index of resolve. • Even if Kuwait produced only “carrots” and the US and others were interested only in oil, they should still have responded to the Iraqi invasion of Kuwait (because UAE, Saudi Arabia, etc., produce oil). • Cf. the domino theory (with reference to Southeast Asia and elsewhere), • which really came to pass in Eastern Europe in the Fall of 1989. • Generalized deterrence (“containment”) was especially important to the U.S. and the West (and to a lesser extent to the S.U. and the East) during the extended conflict of the Cold War. • The Soviet’s major deterrence problems probably lay in Eastern Europe, • just as Russia’s deterrence problems today probably lie mainly in small “national” insurgencies (Chechnya, etc.).

The Art of Decommitment • Suppose D has made a commit-ment to defend some prize against A, • e.g., Quemoy/Matsu islands in the Taiwan Strait but adjacent to the Chinese mainland. • Can D “decommit” without undermining its future credibility? • “This precedent should not be interpreted as a precedent.” • US might hope that an earthquake, tsunami, typhoon, etc., sinks the islands. • “Giving in” to Nature does not imply you will “give in” to adversaries players. • D can (try) to redefine the commitment, • e.g., from Western rights throughout Berlin to Western rule in West Berlin.

DEFENSE, DETERRENCE, AND COMPELLENCE: THREATS, PROMISES, AND CREDIBILITY