The Rise, Decline, and Rebirth of Extra-State Conflicts

NMCB-3 participates in an eight-day jungle training program.
Creative Commons License Official U.S. Navy Page via Compfight

In the most recent update to the Correlates of War (COW) War databases (update to v4.0), the COW project added a new category of war to include wars between non-state actors, bringing us up to a total of four different types of wars: Inter-state, Intra-state, Extra-state, and Non-state wars.  For those who are less familiar with this vein of international relations research, inter-state wars are those that occur between two recognized states.  Intra-state wars are wars within a state between a state actor and a non-state actor within its territory; these are better known as civil wars.  Extra-state wars are those that pitch a state actor versus a non-state actor in some other party’s territory (either another state, non-incorporated territory, or territory controlled by a non-state actor).  While COW has included data on extra-state wars for several decades, there is very little research that focuses on them as a unique or separate type of war.  Of note, scholars, as well as the COW project, have labeled these previously as extra-systemic wars to show that they were between system members (states recognized as such) and actors who were not part of the state system.

Over the course of the COW project’s domain, extra-state wars are more common than one might expect when compared to other wars.  In total, there have been 192 extra-state warsthat is, a state fighting a non-state actor.  Several of these cases are all part of a larger war of one or more states fighting one or more non-state actors; thus, if we only look at these conflicts by the whether or not they are part of a larger campaign, there are 163 such wars.  While perhaps seemingly infrequent, there have only been 95 inter-state wars in the same time period and 334 intra-state wars.  Non-state wars currently clock in at 62 over the last 200 years.

While they are not nearly as frequent as civil wars, they are far more common than inter-state wars: States, in aggregate, are twice as likely to fight an entity in a territory that is not its own than it is to fight another state.  Given the history of state expansion and contraction, this is not overly surprising as states try to expand their borders, acquire resources and people, and grow at the expense of their competitors, but the COW data does not include some of the more active periods of colonization; in fact, the first major wave of European colonization ends by the 19th century, right when the COW project picks up.

Extrastate Onset


These wars typically fall into two different categories: wars of colonization (or conquest) and wars of decolonization.  While the first wave of colonization was over by 1816; new rounds of colonization did happen well through the 19th century.  By the 20th century, while new acquisitions of territory certainly did occur, the wars began to shift towards wars of decolonization.  Territories that were not formally incorporated into states, but still possessed by the states, acted as the battlefields for a new wave of extra-state fighting as people across the globe sought self-determination.  Several pursuits for self-determination, especially into the Cold War, did not occur with a war that killed at least 1,000 people (as per the Correlates of War coding rules), but were much less violent, a few successful attempts we can accurately describe as relatively peaceful.

Extrastate Ongoing test

Why the decline?

In the 3.0 version of the Correlates of War data set on extra-state wars, the last extra-state war started and concluded in 1975 with the Indonesian conquest of East Timor.  The 4.0 dataset is much fuller in this regards and adds several conflicts to the data such that the former definitive end to extra-state conflicts is obscured by new data points.  However, while the 1945-1990 period seems to be active, mostly with decolonization, and there is a lull in the post-Cold War period that starts to pick up again in the early 2000s.  Notably, the two major historical causes of extra-conflicts conflicts are becoming less likely candidates for these wars to occur: colonization and decolonization.  Attempts to colonize non-state territory is increasingly improbable as states claim virtually all inhabited territory. Wars over decolonization are still possible, but they have become increasingly less likely for two distinct reasons.  First, for it to be an extra-state war, the territory is not incorporated into the state itself, but is a possession elsewhere.  Territories that a state has claimed on its border, thereby expanding its borders, in the future do not become extra-state wars, but often become civil wars (if they become a fully-fledged war at all).  Second, these types of possessions are not as common as they used to be as several of the outstanding territorial possessions lack the capacity to fight a full war.  The Falkland Islands currently have a population of nearly 3,000 people, but is unlikely to field all the people necessary to fight a war against the United Kingdom and result in at least 1,000 battlefield fatalities.

Why a resurgence?

A new mechanism exists for extra-state wars to occur and the United States (among several other states) has participated in two such conflicts in the last decade.  Wars over regime change may introduce an arena where a major power that succeeds in changing the regime of another state, can be forced to fight non-state actors during and after transition.  Wars of colonization had a similar transition as well: Often a state would displace an existing government in conquest and continue to fight non-state actors as it attempted to subdue the population; the conquest of East Timor in 1975 follows this pattern.  With the exception of Turkey’s fight against the PKK in Iraq and the Israeli-Palestinian conflict during the al-Aqsa Intifada, the post-Cold War extra-state wars are characterized by regime change. In total, there are five unique cases of post-Cold War extra-state wars, and all of them are in the Middle East/Central Asia. While post-Cold War extra-state conflicts account for only 3% of the population of extra-state wars since the beginning of the 19th century, this could be the harbinger of a new wave of such conflicts (or simply an abnormality).

Both regime change and the pursuit of terrorist groups beyond a state’s borders increase the potential for extra-state wars in the future.  These wars look different from civil wars in that there are two different populations for the state to try to appease: a core population (perhaps a selectorate) within the state and a peripheral population, not strongly connected to the core, that will do some combination of supporting and resisting the actions of the state actor.  This dual-balance of gaining legitimacy for state action is something that works against the state over time (as it does in classical insurgency conflicts) and may deter particular kinds of states (i.e. democracies) from engaging in these conflicts if they expect the conflict to endure.  However, unlike inter-state wars, modeling selection becomes burdensome as it is extremely difficult to conceptualized and identify the domain of all possible, non-state actors outside of a state’s territory. Knowing why a state chooses to enter one particular extra-state war instead of another would be revealing if it were possible to model, but we currently lack the unit of analysis to properly identify possible non-state targets for extra-state war.

Regardless of the continued salience of extra-state wars, the ratio of literature that exclusively focuses on extra-state wars compared to the number of such wars that we have tracked pales in comparison to the literature that covers intra- and inter-state conflicts.  These wars offer a fruitful avenue for further exploration.


Michael A. Allen

About Michael A. Allen

Michael is an Assistant Professor in Political Science at Boise State University with a focus in International Relations, Comparative Politics, and Methodology (quantitative and formal). His work includes issues related to military basing abroad, asymmetric relations, cooperation, and conflict. He received his Ph.D from Binghamton University in 2011.

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