Think ISIS is unique? Think again.

If there's one thing that almost everyone seems to agree on about ISIS, it's that it's a major — even historically unique — threat to global security. John Kerry called the group "a profound and unique threat to the entire world." The UN Security Council unanimously adopted a resolution saying ISIS is an "unprecedented threat to international peace and security."

But many experts on insurgency and terrorism see things differently. Far from being "unprecedented," ISIS is actually quite similar to past militant groups, in terms of both the tactics it uses and its ability to control territory. In a recent article in Perspectives on Terrorism, Stathis Kalyvas, professor of political science and director of the Program on Order, Conflict, and Violence at Yale University, cautions us to be skeptical of "claims of ISIS exceptionalism." Instead, he says, we should see ISIS as building on what past insurgents and terrorists have done — particularly "revolutionary" militants like the radical Marxist-Leninists of the Cold War.

Kalyvas is perhaps the leading global expert on insurgencies, so it's worth taking his ideas seriously. As such, I called him up to ask why he thinks it's wrong to talk about ISIS as unique, what we can learn about ISIS by looking at the past, and what the historical lessons tell us about the prospects for victory against ISIS. What follows is a transcript of our conversation, edited for length and clarity.

Zack Beauchamp: Everyone — politicians, the media, etc. — says ISIS is a threat like nothing we have ever seen before. But you don't think that's true. Why?

Stathis Kalyvas: The idea that something is completely new tends to be very common: It's almost an automatic response to things viewed as new and threatening. But it also almost always tends to be wrong.

I think the main way in which we've understood or have tried to make sense of ISIS is through the lens of militant Islamists of a very specific ideology, or Islam in general — so from a religious perspective or through the lens of terrorism and secular violence.

But if we take a more detached perspective, a more historical one, they share a lot of common elements with groups that have incorporated in the past. The key idea [they share] is that you can have a sort of radical utopia as your main goal and act upon it. That, in a sense, is what has been driving a lot of revolutionary groups throughout history.

Just in the modern period, you have the anarchist groups that emerged at the end of the 19th century. In the 20th century, you have the much more common Marxist-Leninist groups, either insurgent groups or terrorist groups that appeared, for example, in Western Europe — especially in Italy and Germany during the 1970s. Even though the factions have varied quite a lot, there is a common thread: A radical utopia is at the center of their identity as groups.

So we've seen similar combinations, similar types of groups emerge in the past: Almost no new group is completely unrelated to anything that has come in the past, in terms of its activities. That's why I don't think ISIS is something completely novel, even though its combination of elements might be original.

ZB: Have any of these "revolutionary" groups, as you term them, had ISIS's combination of both governing territory as well as interest in conducting terrorist attacks around the world?

SK: We have a lot of cases in which insurgent, territorial groups also undertake what we call terrorist attacks within the same country. Usually, the criteria that determines whether they do that is where they control territory. For example, if you think about the Shining Path [Sendero Luminoso] centered in Peru: In the areas in which they have territorial control, they acted as insurgent groups. But very often they bombed and killed a lot of people in Peru's big cities like the capital, Lima [which they didn't control]. So that's very common, and we've seen that kind of activity throughout history.

To cite another very well-known example: The National Liberation Front (FLN) of Algeria that was against the French used an insurgent strategy in the countryside with guerrilla tactics. At the same time, they used terrorist attacks in the city of Algiers.

It's less common for groups to undertake combined action in their territory and conduct transnational terrorism, but even that is not completely uncommon. For example, the Palestine Liberation Organization in 1970s undertook territory-based actions (for example, in Lebanon, where it had a territorial presence) and then undertook international terrorism in Israel and Western Europe. So even that combination is not as novel as we sometimes think it is.

ZB: So how successful have these other, similar revolutionary groups been? And what can that tell us about ISIS?

SK: There have been revolutionary groups that have won civil wars using a combination of different tactics. For example, the Chinese Communist Party was a revolutionary group that took over China.

After taking over, they implemented their program. Sometimes, it was less radical than expected. Even when it was very radical, in time a lot of these groups tended to become less radical — they normalized their policies. There is, again, a long history of those kinds of processes.

ZB: ISIS doesn't exactly seem like the type to moderate its platform. Do you think it looks more like the successful or failed revolutionary groups from the past?

SK: Kinds of groups described generically as "jihadi" or "Salafi" groups have been particularly unsuccessful as revolutionary groups, both territorially and non-territorially.

On the territorial front, we have a number of times those groups tried to take over countries by using guerrilla war. That includes the insurgency in Egypt in the 1990s or the GIA in Algeria. We have some evidence that this failure results from their extreme radicalism. It didn't resonate with local populations, on one hand, and it also made it difficult for them to find an external sponsor to support them. These failures resulted in the turn to the international terrorism of al-Qaeda that we know.

ISIS is taking advantage of the situation in Iraq and Syria in order to return to more traditional territorial tactics. And what we've seen lately, insofar as ISIS is indeed the organizer of the terrorists in France, is an adoption of a double kind of tactic of transnational terrorism outside of Syria and Iraq and much more traditional rebel and insurgency tactics in Iraq and Syria.

Generally speaking, terrorism is a weapon of absolute weakness. It signals an inability to capture territory because, at the end of the day, most groups really want to take over countries and apply their program. That requires territorial control. Terrorism becomes necessary because that's the best they can do.

If you think about cases like ETA in the Basque Country in Spain, the Red Brigades in Italy, or the Baader-Meinhof group in Germany, their ideal choice was to launch an insurgency. But because the states they were fighting against were so strong and the society in which they emerged was urbanized, that possibility could not materialize. As a result, they decided to fight using clandestine terrorist tactics.

In every case where this kind of policy was implemented by revolutionary groups (as opposed to nationalist or secessionist groups), they were not able to get anything out of it.

ZB: When you are looking at the history of revolutionary groups, specifically ones that both held territory and engaged in terrorist tactics, what typically works to defeat them? And what does that tell us about the ISIS fight?

SK: There are different tactics depending on the tactics the rebel groups used. If the rebel group uses guerrilla war in order to conquer territory, then you have various forms of counterinsurgency — and if you look at the cases of insurgency, the majority of cases have been won by governments.

If, on the other hand, you are looking at small clandestine groups that operate in the midst of usually urban milieus, in those cases you need police tactics — the gathering of intelligence, the ability of intelligence services to penetrate these groups, to anticipate their actions. This is something that takes a long time. But there is quite a long history, especially in Western Europe, of how to disrupt terrorist activities in a way in which democratic liberties are not sacrificed.

I think it is a mistake to mix the two facets of ISIS — the terrorist one and the territorial one. I don't think it is a good idea to bomb Syria in order to anticipate terrorist attacks in Western Europe or elsewhere. Even though there is a connection between the chain of command in Syria and Iraq and the actual operatives on the ground in Western Europe, very often the kinds of individuals who get involved in situations are not necessarily the same.

ISIS has an army in Syria and Iraq that's composed of various elements — that includes foreign fighters and assorted radicals, but also very often individuals who are recruited on the ground for local reasons. You fight against those using counterinsurgent tactics.

On the other hand, the job of trying to prevent terrorist attacks in Western European countries and elsewhere has to be addressed in a way that's mobilizing intelligence services and police work — very much like how Western Europe and the United States have dealt with threats in the past.

So the two problems are politically connected, but from a technical perspective, I don't think they are same, and you shouldn't attempt to solve one by targeting the other. Rather than bombing Syria in order to avert future terrorist attacks, you should focus your energies on terrorist cells operating in Europe and preventing those from acting in the future.

ZB: ISIS is interesting because unlike most previous iterations of jihadist groups, it's staked its legitimacy and its identity claim very clearly on the notion that it controls territory and it is capable of governing. Given this ideological component of the group, how effectively do you think it could switch modes into fighting a guerrilla or unconventional insurgent war as opposed to the conventional war it has been fighting so far?

SK: I think even though they've made those associations and they emphasize their state, in practice they're not that different from any groups that have held territory. What we see very often is that those groups promote a sort of radical utopian ideology, but much of their actual practices on the ground are not particularly radical or revolutionary.

The way ISIS governs is very much based on trying to tax the population, trying to provide public security, sometimes hatching deals with minorities where in exchange for some taxation they won't harm them. I don't see anything in terms of their behavior, except their spectacular violence and use of social media to entrance the world, that's particularly unusual in the way in which they run the territory.

So what happens if they lose control of this territory? Two things happen. The first is they are defeated and they cease to exist, and they go through a crisis and fragment and you get various splinter groups fighting against each other and you get a very long half-life and a very low-level entity.

The second is that they try to reorient their action and perhaps use transnational terrorism as an alternative. But, again, that option doesn't really provide them with any real leverage, any real advantages. It's just a way to continue to exist.

Now, it may be that if ISIS is defeated on the ground, the group as such would disappear and then another type of jihadist group would emerge performing different strategies. Or it may be that a defeat on the ground may have more long-term effects. It's very difficult to predict the outcome of these groups. But I will generally say that ideological movements that manage to mobilize enough people tend to have quite a long life.

ZB: What else would you say could be done to weaken ISIS?

SK: Perhaps the best way to delegitimize them is to allow them to govern and to show that in practice, they cannot solve any problems. That their utopias are precisely that — utopias.

That is a double-edged sword, because if you allow them to govern a territory and form a state, you create an island that allows them to sponsor other insurgent movements. But governing a territory is very often the Achilles heel of radical ideologies, as it proves that in fact there are very, very clear limitations on what you can do.

ZB: One last question. You've mentioned a number of different insurgent groups or terrorist groups as potential parallels to ISIS — could you pick one specifically that is an especially good comparison? I'm just curious to see where you find the parallels and what that story tells us about the ISIS story.

SK: That's a very interesting question. I haven't thought carefully about that.

In terms of the combination of ruthless territorial tactics, on the one hand, and terrorist tactics on the other, I would say that the Tamil Tigers [LTTE] would be a very interesting parallel. With them, the difference is they were primarily nationalist and secessionist — so they didn't really recruit along a very large swath of ideological fellow travelers. Their reach was limited by their ethnic group: the Tamils of Sri Lanka.

But in terms of the ability to combine the two-pronged strategy — terrorism outside their heartland and then institutionalization by creating an army and administration in their territories, I would say that's an interesting parallel. [Editor's note: The Tamil Tigers were crushed, quite brutally, by the Sri Lankan government in 2011 after a very long insurgency.]

Now, in terms of the group that would have ISIS's specific combination of violence and radical utopia, I'm sure there are plenty of examples. But I'll have to think more carefully about the pool of potential comparisons here.