Security dilemma

In international relations, the security dilemma (also referred to as the spiral model) is when the increase in one state's security (such as increasing its military strength) leads other states to fear for their own security (because they do not know if the security-increasing state intends to use its growing military for offensive purposes). Consequently, security-increasing measures can lead to tensions, escalation or conflict with one or more other parties, producing an outcome which no party truly desires; a political instance of the prisoner's dilemma.

The security dilemma is particularly intense in situations when (1) it is hard to distinguish offensive weapons from defensive weapons, and (2) offense has the advantage in any conflict over defense. Military technology and geography strongly affect the offense-defense balance.

The term was first coined by the German scholar John H. Herz in a 1950 study. At the same time British historian Herbert Butterfield described the same situation in his History and Human Relations, but referred to it as the "absolute predicament and irreducible dilemma". The security dilemma is a key concept in international relations theory, in particular among realist scholars to explain how security-seeking states can end up in conflict.

Tang identified the following core components between interpretations of the security dilemma by Herbert Butterfield, John H. Herz, and Robert Jervis:

Butterfield viewed the security dilemma as the root cause of all war, but he did not view anarchy as being the ultimate source of the security dilemma. Instead he attributed the source to fear and the "universal sin" of humanity — that humanity can commit evil. Herz and Jervis did not view the security dilemma as being the root cause of all war. A counterexample frequently given is the Second World War, where there was no dilemma over war with a malign Nazi Germany.

The security dilemma is the core assumption of defensive realism. According to Kenneth Waltz, because the world does not have a common government and is "anarchic", survival is the main motivation of states. States are distrustful of other states' intentions and as a consequence always try to maximize their own security. The security dilemma explains why security-seeking (as opposed to non-security seeking) states could end up in conflict, even though they have benign intentions.

The offense-defense balance accounts for why the security dilemma is more intense in certain circumstances. Defensive realists argue that in situations where offensive actions have the advantage (for example, due to geography or military technology), the security dilemma will be particularly intensive because states will be more distrustful of each other and be more encouraged to take preemptive offensive actions. In situations where the defense has the advantage, security-seeking states can afford to focus strictly on their defense without as much fear of being attacked. Security-seeking states can also signal benign intentions without adversely affecting their own security.

Defensive realists often regard the success of the United States in World War I as being a result of the defensive approach taken by the United States. Had the United States taken an offensive stance, defensive realists argue that the United States would not have been secure. The conclusion from defensive realism is that in some circumstances states can escape the security dilemma.