Let's consider situations when country A wants to deter country B from doing some action (i.e. the USA wants to deter China from attacking Taiwan).

Such situations can be modeled in the following way. In case B does something A does not want it to do (i.e. attack Taiwan), A can make either a soft response, which is less costly to A but also cases less harm to B (i.e. send thoughs and prayers and impose some sanctions) or a hard response, which is more costly but also cases more harm to B (i.e. commit to enter the war on Taiwan's side). A knows what is the optimal response, but B can't observe this but can make probabilistic guesses. Two options are possible:

  1. A thinks that the hard reponse is optimal. If A won't publicly commit to make the hard response, B might think that there is some of probability of soft response happening, so the expected costs will be lower (compared to the case when A has commited to make a hard response), so B will be more likely to do the action. So it's optimal to make a hard response.
  2. A thinks that the soft reponse is optimal. If A won't publicly commit to make the soft response, B might think that there is some of probability of hard response happening, so the expected costs will be higher (compared to the case when A has commited to make a soft response), so B will be more likely to do the action. So it's optimal to make no commitments (= strategic ambiguity).

So the equlibrium of this game is that if A is ready to make a hard response, they'll say it and won't use strategic ambiguity. If A is not ready, they will use strategic ambiguity (and everyone will be guessing that A plans a soft response).

Is the model above accurate enough to truly predict that strategic ambiguity = soft response, or are there some cases when such prediction is wrong?

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    This is going to depend on not only the countries in question but the situation that is in question at well. How a country will respond will depend on the country they are responding to as well as what they are responding to.
    – Joe W
    Oct 28, 2022 at 21:00
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    You're assuming there are only 2 responses, hard and soft. In reality there are more. If you consider the US defending Taiwan, the range would go from minor sanctions, to sending warships to deter invading forces, to attacking military targets on mainland China, to full nuclear war.
    – Stuart F
    Oct 28, 2022 at 21:48
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    This seems a question about game theory or military strategy rather than politics; I'm not sure if there's a better place on SE to discuss such models.
    – Stuart F
    Oct 28, 2022 at 21:48
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    Speculation (and therefore not an answer): a hard response is expensive and therefore has a higher threshold. A commitment to a hard response might tell B it's safe to act just below the threshold for a hard response, without getting any response. Oct 28, 2022 at 22:05
  • In addition to JoeW's comment, I don't think we have that much history to draw on. Traditionally, this kind of guarantee would have been in the form of a treaty with firm commitments. With China/Taiwan however, US intent at the time was to draw China away from USSR. And it couldn't get a treaty with a non-recognized state (Taiwan). So US ended up getting that non-treaty treaty in very different circumstances. And not because it wanted to signal soft or hard intent. Oct 29, 2022 at 1:56

4 Answers 4



Ambiguity leaves the way open to a soft response without breaking public promises, because there were none. But ambiguity might also mean that a forceful response will come to "unacceptable" actions, and that it is not spelled out exactly what "not quite unacceptable" means in this context. This would prevent the aggressor from staying "safe" by staying below the declared level of intervention, yet inflict ongoing, painful damage.

Think back to the first stages of the Russian attacks against Ukraine. First it was supporting separatists. Then it was "little green men" without flags on their uniforms. Then it was regular forces and Russia declared an annexiation of Crimea. This kind of gradual escalation was calibrated to prevent a forceful response by the international community. Had Ukraine been protected by a promise with "strategic ambiguity," Russia might have worried that even "little green men" are crossing the ambiguous line.

  • The properties of that crocodile-repelling amulet were never tested. You never know if your deterrence has worked or if the other side had no actual intent.
    – alamar
    Oct 29, 2022 at 6:35

Is the model above accurate enough....

No. Right off-hand I can think of two major things missing from your model.

  1. The costs of any particular response vary over time as many other parts of the situation change (e.g., the amount of domestic support for a particular international action). So A does not actually know what the optimal response will be at some future time should B perform the unwanted action.

  2. There are other other actors involved: A's response will also depend on what C, D, et al. are willing to support at that future time. And even further, as Readin points out in a comment below, A may be trying to calibrate the response in one direction for A, and in another direction for C.

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    Let's also toss in that A may be trying to prevent C from taking actions that will make B more likely to attack. In the example used to justify the model, America doesn't want Taiwan taking actions that will make the China more likely to invade. That is, America doesn't want Taiwan to rewrite its constitution, change its official name ("Republic of China"), or anything else that would be seen by China as a blatant move toward formalized independence. If America were to guarantee protection for Taiwan, then Taiwan might be emboldened to do such things then China might attack drawing America in.
    – Readin
    Oct 30, 2022 at 5:44

Strategic ambiguity leaves you with more options while only marginally reducing the strength of deterrence.

Let's stay with the China-US-Taiwan example and with your nomenclature A (US), B (China) and C (Taiwan).

B declares interest to invade and occupy C. Neither A nor C are actually willing to allow that although it's unsure how much A (being a democracy) is actually willing to pay a price for it. A and C mostly want to deter B from attacking C but B may still decide to ("call the bluff") attack C because B may bet that A would pull out.

In your scenario 1, A unambiguously warned B before that if B attacks C, A will join C's side. But A is a democracy. How can it credibly promise to do something in the future? In a democracy, decisions about going to war will always be decided by Parliament and are unforeseeable. The unambiguous warning in the past from A to B may prove more like an empty promise, may even make A look weak if A goes back on his own words and might make C feel kind of betrayed.

In your scenario 2, A ambiguously stated that it might or might not side with C in case B attacks C. To me, that counts as almost the same strength of deterrence (B has to factor in a potential taking part of A in a war against C) but with much more options for A. All possible decisions by the democratic system of A would be covered by the ambiguous statement, so nobody can say that A delivered less than promised. Also A can decide to support C only partly or join later on and increase support. A has a lot of strategic possibilities.

To make it more specific: If China for example decides to test the water and occupy a small island in front of Taiwan or to blockade Taiwan, the US can initially withhold their forces and not directly confront China under strategic ambiguity in the hope that the situation can be saved at the last minute. On the other hand if they declared unwavering support, they might be forced to take part in an escalatory spiral leading to destruction and a direct war between A and B. That are the advantages of strategic ambiguity even if the deterrence effect might be slightly less (but not that much less because in a democracy you cannot promise anything about the future anyway).


I suspect the real purpose of "strategic ambiguity" is to avoid issuing threats or brandishing weaponry in such a way as to corner the opponent into responding with an immediate attack.

Also, given that the only overwhelming military weapon the US has against Russia is ending the world for everyone (i.e. a suicide bombing), and given that the US population have no appetite to cook regardless of the fate of Ukraine, the US are really on considerably weaker ground than it may appear.

If anything, their purpose is to try and confine the situation to a prolonged and grinding proxy conflict, during which something eventually fractures in Russian society and Putin's regime folds due to the release of internal forces.

At worst under these circumstances of proxy war, the West lose and forfeit Ukraine. At best, they win Ukraine and Russia folds into chaos.

The West would have much worse problems if Putin dropped the bomb, and their only choice then is to either accept the fact or end the world.

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