This Freakonomics podcast says the number one reason for terrorism is military occupation.

Robert Pape says that the overwhelming reason for 'suicide' (homicide) bombers is occupation by a foreign power or desire for local autonomy against a larger state, rather than religion.

PAPE: Military occupation is the root cause of suicide terrorism. And there are two types of military occupation. There is a foreign, very distant or external occupation, such as when the United States occupies Iraq. And then there can also be an internal occupation, such as when one group occupies another group, such as in Iraq today.

Additional info: http://danieldrezner.com/research/guest/Pape1.pdf

So why did the Islamic State attack Belgium?

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    The article by Pape is from 2003.
    – user7680
    Commented Mar 26, 2016 at 10:48
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    ... Because extremism doesn't come in "rational". Commented Mar 26, 2016 at 21:06
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    Wikipedia states that Belgium is fully military involved in the war agains IS. Commented Mar 27, 2016 at 8:20
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    @EricTowers Extremism can be very rational. International Relations Game Theory 101. Check out the episodes on guerrilla warfare.
    – Chloe
    Commented Mar 29, 2016 at 22:51
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    @Chloe : Guerilla warfare is not extremism. Guerilla warfare is tactics and is largely dictated by the opponents, not by the guerillas. Commented Mar 29, 2016 at 23:02

7 Answers 7


Because Pape doesn't know what he's talking about.

Islamic jihadist groups Boko Haram and Al Shabbab terrorize African communities in Kenya, Nigeria, Mali, Somalia, Chad, Cameroon, Niger, and Tanzania- which of those countries is engaged in military occupation?

The Iraqi Yazidis are terrorized by ISIS - and they don't even have a state or army.

Or how about all the Pakistani Christians blown up by the Taliban this week- for celebrating Easter?

You don't need to listen to data-crunching professors to understand ISIS- they explain themselves very clearly: The official ISIS magazine spells out their intention to eliminate the "gray zone", in order to divide the world into two camps: Islam vs the Infidel.

And here's some choice cuts from their official spokesman:

O crusaders, you have realized the threat of the Islamic State, but you have not become aware of the cure, and you will not discover the cure because there is no cure. If you fight it, it becomes stronger and tougher. If you leave it alone, it grows and expands.


Blood becomes legal to spill through disbelief. So whoever is a Muslim, his blood and wealth are sanctified. And whoever is a disbeliever, his wealth is legal for a Muslim to take and his blood is legal to spill.

The big lie is that all this terrorism is somehow a response to bad behavior by the West. In reality the vast majority of Islamic terror victims are the minority populations of Muslim-majority countries: Copts in Egypt, Bahai's in Iran, Animists in Sudan, Assyrians in Iraq, Shiites in Sunni countries, Sunnis in Shiite countries, Jews anywhere...

And it doesn't matter what the West does, because they'll always find a reason- there are a thousand ways to piss off an Islamist:

So even if we pulled out from every last place on earth, solved the Israeli-Palestinian conflict, and walked on egg-shells until the end of time, any random idiot posting a Mohammed video on YouTube would still give them all the justification they needed to shoot up an office or bring down an airliner.

While we're at it, let's dispel a final myth: that these terrorists represent a lunatic fringe, an tiny minority that has no popular appeal in the Islamic world. And yet, as I write this, twenty-five thousand protesters are marching in a single city in Pakistan, in FAVOR of killing people for blasphemy. Is it any wonder terrorists don't have a recruiting problem?

Which brings me to my final point- there's a difference between having political grievances and being batshit crazy. It's time to stop thinking of Islamists as just another religious/political/ethnic faction, that can be reasoned with or appeased, and start treating them like insane death cult that they are.

If you want to read some people who actually do know what they're talking about, try:

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    Page 37, Shaykh al- ‘Adnānī said, “Likewise, we renew our call to the muwahhidīn in Europe and the disbelieving West and everywhere else, to target the crusaders in their own lands and wherever they are found. We will argue, before Allah, against any Muslim who has the ability to shed a single drop of crusader blood but does not do so, whether with an explosive device, a bullet, a knife, a car, a rock, or even a boot or a fist. Indeed, you saw what a single Muslim did with Canada and its parliament of shirk, and what our brothers in France, Australia, and Belgium did.
    – Chloe
    Commented Mar 27, 2016 at 1:17
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    Page 73, DĀBIQ: Why did you go to Belgium? ABŪ ‘UMAR: Alhamdulillāh, Allah chose me, Abuz-Zubayr al-Baljīkī (Khālid), and Abū Khālid al-Baljīkī (Sufyān) to travel to Europe in order to terrorize the crusaders waging war against the Muslims. As you know, Belgium is a member of the crusader coalition attacking the Muslims of Iraq and Shām.
    – Chloe
    Commented Mar 27, 2016 at 1:18
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    Regarding "ISIS explain themselves very clearly": at thenation.com/article/… Pape says that "religious fervor is not a motive unto itself. Rather, it serves as a tool for recruitment and a potent means of getting people to overcome their fear of death and natural aversion to killing innocents." and "ISIS’s goals, like those of most terrorist groups, are distinctly earthly". So I think even if ISIS claims to be motivated by religion it doesn't mean that's their true, actual motive.
    – oliver
    Commented Mar 27, 2016 at 9:22
  • This, and the fact that Salah Abdeslam got arrested : the risk of him betraying them was too great to continue waiting or go bomb a far away place. They didn't necessarily planed to bomb Brussels initially!
    – Shautieh
    Commented Mar 28, 2016 at 4:30
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    @oliver Legitimate observation, but attaching motives to people is a tricky business. When you mention “true, actual” motives, it would be better to describe that as the machinations of an inner group that operates behind a façade. Understanding the motives of organizations, which are often greater than the sum of their parts, is even more difficult: it may be that no one person, in ISIS or out of it, understands how the modular motivations of every person in relation to ISIS influences its massive modus operandi. That is especially applicable the more an organization resembles a swarm. Commented May 9, 2017 at 18:17

First of all, ISIS claims that "killing kafirs is always good".

Official ISIS Announcement on Brussels Attacks

First we want to make it clear to all that what makes the kafir’s blood permissiable to spill is not him fighting the Muslims, rather it is his “KUFR” that necessitates his killing. So if one asks, can you kill a Kafir (who does not fight Islamand muslims)? the answer is a big YES

That naturally applies not only to "kafir people", but to "kafir states" too. So it doesn't matter what Belgium did (or not) before attack.

Next, Belgium participated in anti-ISIS coalition earlier.

Wiki: American intervention in Iraq (2014-present)

The Building Partner Capacity (BPC) program is meant to help the Iraqi government to prepare forces for the counter-attack against ISIL and the regaining of its territory. Australia in April 2015 committed 300 military personnel to the BPC training mission in Iraq. According to the U.S. Department of Defense, by May 2015 a dozen countries had committed themselves to the BPC program: Australia, Belgium, Denmark, France, Germany, Italy, Netherlands, New Zealand, Norway, Spain, United Kingdom and United States. By May 2015, the program had trained 6,500 Iraqi forces.

Next, Belgium was probably a primary base for terrorists who performed earlier attack in Paris. Which means that ISIS already had people, arms, explosives etc. in Belgium. It was only a matter of time when they attack Belgium itself.

And, finally, there is an unconfirmed assumption that Brussels attacks could be a secondary plan for terrorists: after Salah Abdeslam was arrested on 18th March, the remaining terrorists decided to attack nearby targets in Brussels, before they all got arrested by Belgium police. That leaves open a possibility that at this point ISIS is less interested in an attack on Belgium than, say, another attack on France.

Yet the real conclusion is that terrorists always pose a threat to everyone they can reach. So Brussels was in danger all the time they resided in it.

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – yannis
    Commented Mar 29, 2016 at 9:44

There's a big assumption in the question. Was Belgium the original intended target?

Or did these terrorists, who were mostly from Brussels and had been using Brussels as a base since before the Paris attacks, for many reasons, particularly disorganised security...

justice system and intelligence services are split... six different police zones... information sharing more difficult... tiny security apparatus...

...then hastily make Brussels their target after suddenly finding themselves on the brink of arrest?

In other words, there may have been no strategic reason to target Belgium, only strategic reasons to target other countries from Belgium - but then suddenly they found themselves needing to improvise (while in Belgium).

Update: After this answer was written, some more supporting evidence emerged. Here's CNN's write-up of that revelation:

The cell that carried out the Paris and Brussels attacks sought to target the Euro 2016 soccer championships in France, ISIS terror suspect Mohamed Abrini has told interrogators, according to a source close to the investigation


When the terrorists discovered the French were moving fast in their investigation, they changed their plans, the Belgian prosecutor's office said.

"Eventually ... they urgently took the decision to strike in Brussels," the office said.

There's plenty of evidence suggesting that the attacks on the metro and Brussels airport were rushed, bought forward or improvised in response to changing circumstances.

  • Their explosives were unfinished. Chemical components for explosives, bombs, incomplete bombs and components for nail bombs were found that hadn't been used, as well as guns (e.g. with Mohamed Belkaïd)

  • They were mostly already terrorist suspects whose cover had just been blown. The Bakraoui brothers and Najim Laachraoui had been named in connection with the Paris attacks, their collaborator Mohamed Belkaïd had been killed and items of his found, and the attacks came just 3 days after Salah Abdeslam had been arrested, with the media initially describing him as being "co-operative". As the BBC put it:

    Police made clear he was providing information and his jihadist collaborators will have worried that their cover had been blown.

  • The airport bombers used an unsuitable vehicle. The cab driver reported refusing to take an extra bag because there wasn't space. This suggests less than meticulous, possibly hasty, planning.

  • The death toll per attacker was also relatively low compared to comparable attacks such as Paris, or to pick the most recent examples, the single explosion in Lahore which just killed 50 people, or the solitary suicide bomber killed 29 in Iraq earlier this week). This looks likely to be single figures per attacker.

  • A note left by an attacker Brahim el-Bakraoui actually explicitly states that he acted because he was afraid of being arrested and was sick of being on the run. Brahim had been deported from Turkey for ISIS links and was known to authorities, and his brother Khalid had been named as a suspect in connection with the Paris attacks due to having rented one of the properties used in its planning. The BBC translate the note as saying:

    I don't know what to do, I am in a hurry, I am on the run, people are looking for me everywhere and if I give myself up I will end up in a cell

Given all the above, it would be more surprising if the terrorists' plan hadn't changed than if it had changed.

If Brussels wasn't the original target, being based in a well connected hub at the heart of Western Europe, their intended target could have been almost anywhere.

There are many theories about what the original intended target may have been. One is, the major Euro 2016 football tournament to be held in France. The BBC also suggest an intended Easter attack:

It is suggested he was part of the IS Belgian cell preparing attacks timed for Easter but when [Salah Abdeslam] was caught they were brought forward.


ISIS has limited options, they can't strike at just any location they would ideally want to hit. ISIS has to recruit people who are willing to do their bidding, these people have to be able to make bombs and be able to carry out a successful attack. They have to be able to form a network that won't be noticed by law enforcement. This means that ISIS will recruit in places where there are many radicalized Muslims where there the local community and the local authorities don't get along well.

In such places where you have a lot of unemployment where there are many addicts, homeless people and drugs dealers, people are unlikely to notice that in the house next door someone is making a bomb. In Brussels and Paris there are quite a few areas that are like this, that's then the ideal place for ISIS to gain a foothold as it's also close to high value targets.

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    This answer deserves to be much higher voted. To strike near home requires much less logistical effort than to prepare an attack elsewhere. Commented Mar 27, 2016 at 17:50
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    The attacks on Paris were not organized from Paris
    – Vahx
    Commented Mar 29, 2016 at 12:07

Brussels is also the center of Europe, and therefore a desirable symbolic target. From both the ISIS terrorist's point of view and that of Europe's warmongering elite, looking for public support for their future endeavors.

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    This is not an asnwer. Please consider to extend more with arguments and sources.
    – nelruk
    Commented Mar 26, 2016 at 2:38
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    @nelruk -- Brussels is a de facto capital of the European Union. It is therefore reasonable to say that it is "the center of Europe".
    – Jasper
    Commented Mar 26, 2016 at 4:50
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    @nelruk: You may not think that this is a particularly good answer, but it most certainly is an answer. Commented Mar 26, 2016 at 16:05
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    @Jasper nelruk does have a point. What he said might be correct, but it needs something to let an uninformed reader know that he's not just speculating or guessing. Commented Mar 27, 2016 at 3:03
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    It's an answer. It answers the question. It may or may not be correct (I don't know what motivates these lunatics to do what they do). If you think it's not a good answer, feel free to click the little downward-pointing triangle. Commented Mar 28, 2016 at 4:44

Here are some stats from the University of Chicago (Chicago Project on Security and Terrorism):

1 - Attacks by location:

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2 - Attacks by year:

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3 - Attacks by campaign:

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And here are the contribution of each attack vector (i.e: casualties by weapon used):

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In other words:

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These organizations are taking advantage of several factors:

  1. Counterterrorism costs a lot more than terrorism: the tracking and elimination cost per terrorist is pretty high (mobilization, intelligence, means, waiting, etc).
  2. It only takes one successful attack to make a return on investment.
  3. Time is in their favor and the state has more to lose.

Fact: Islamic terrorism has killed more Muslims than people from whatever is considered an enemy (intellectuals, Western Civilization, Atheists, Unicorns, etc).

In my country, they used to slaughter intellectuals, engineers, doctors, politicians, journalists, security forces, and then the people. i.e: Whoever has a brain, can fight them, or is thinking of turning their backs to them.

Most people don't really understand terrorism. Even "experts" I see on TV are really, really, naive about it. This naïveté is both good news and bad news: Good news because it's cute someone who can't think on a cruel enough level to be able to discern the truth, bad news because you don't want someone supposed to be an expert on terrorism think without abstracting human descency.

You can't afford to think like a "normal" human being. Strip down the veneer of religion, strip down the stereotypes, shed light on contradictions between what these terrorists claim and their action, forget everything you think you know about terrorism, and you'll see that it has absofuckinglutely nothing to do with morals, religion, rights, oppression, etc. It's only about power. Who gets what. What's in it for me. That is absolutely it. One of the rare pieces that actually scratched the surface is What if Everything You Know About Terrorism Is Wrong.

It's just asymmetric engagement. People are too emotional about it and concentrate on what the terrorists wear and how they look, the language they speak and the religion they have.. Just make an abstraction for a second and forget about all of that. Keep the essentials, von Clausewitz and all.

Now, it takes a lot of effort to go to college or work to become something.. But it takes no effort to stop shaving and becoming a terrorist. Bonus points if you're illiterate. In a split second, the village idiot who's never read anything in his life (not even the book he swears by and willing to kill for) is in charge of people, because he's violent and the M.D. is not. "Payback time, baby" is what goes in his head. All those people he envied and hated.. now he can do whatever he wants. He has God, remember? He can also rape children, women, his jihadist brothers, and whoever he wants..

Fact: do you know there are a lot of "jihadists" who go AWOL because the group has made them sex slaves. They sign up to kill people and end up washing clothes, making food, and being raped by the group.

Sounds silly? It does for people who've only seen terrorism on TV or in a couple of attacks. But it is exactly how it goes everywhere on a micro level.

Here, I'm talking about the simpletons. The ones who get sent blow themselves. I'm not talking about the Treasurer or the Strategist/Architect (some of the titles that do exist in their organizational chart).

To sum it up: look beyond what they wear and say.

  • Well written, the line about power sums it up well.
    – Phil Lello
    Commented Mar 30, 2016 at 21:08

Some believe that Islamic State's ultimate goal is for the world to end in an apocalyptic war. In order to fight a war you need an army. In order to form an army you need to recruit. The easiest way to recruit is through media attention, and to get it, you simply have to continue to do things that the media will cover. It doesn't matter what you do, because as long as your name is mentioned, then someone out there will want to join your group, or donate to it. If your ultimate goal is to die anyway, then you can do literally anything to keep your name in the news. For every 1000 people (worldwide) that scorn you for it, there may be 1 or 2 people that think it was cool. The goal is to stay relevant and keep recruiting those 1 or 2.

In this case Belgium just happened to be where they were. They may have believed they were on the verge of being caught so they just did something to get more media attention ASAP.

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