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How Many Fighters Does the Islamic State Really Have?

February 9, 2015

Estimates of the number of fighters in the ranks of the Islamic State in Iraq and the Levant (ISIL) are extraordinarily wide-ranging. On the low end of things, CNN’s Barbara Starr recently reported that “U.S. intelligence estimates that ISIL has a total force of somewhere between 9,000 to 18,000 fighters.” In late 2014, the CIA’s estimate of ISIL’s numbers was slightly higher, as its analysts assessed that the group had between 20,000 and 31,500 fighters between its Iraq and Syria holdings.

Other estimates are far higher. Rami Abdel Rahman, the director of the Syrian Observatory for Human Rights, has said that ISIL has more than 50,000 fighters in Syria alone. The chief of the Russian General Staff recently said that Russia estimates ISIL to have “70,000 gunmen of various nationalities.” In late August of 2014, Baghdad-based security expert Hisham al-Hashimi claimed that ISIL’s total membership could be close to 100,000. By November, Fuad Hussein, the chief of staff to Kurdish president Massoud Barzani, told Patrick Cockburn of The Independent that the CIA’s estimates were far too low, and that ISIL had at least 200,000 fighters.

Given this range of estimates, questions naturally arise: Who is right? Which estimate is closest to ISIL’s true numbers? To assess these questions, it’s necessary to consider which parts of ISIL’s force the estimates are attempting to count, the total amount of territory ISIL is occupying, and the attrition that coalition forces have inflicted upon ISIL. Bearing in mind all of these factors, it becomes clear not only that the high-end figures are plausible, but also that they are far more likely than the unrealistically low numbers propounded by U.S. intelligence.

The figure of 200,000 ISIL fighters advanced by Fuad Hussein includes support personnel (ansar), police-style security forces (hisba), local militias, border guards, paramilitary personnel associated with the group’s various security bodies (mukhabarat, assas, amniyat, and amn al-khas), and conscripts and trainees. The actual number of ISIL front-line and garrison fighters is much lower, which are divided between their regular forces (jund), the elite paramilitary (inghimasiyun, which alone may have up to 15,000 members), and death squad (dhabbihah) personnel. Unless one is able to objectively evaluate these bodies, merely throwing out raw numbers is meaningless.

Turning to ISIL’s holdings, it’s worth reviewing the territories that ISIL is believed to occupy in Syria, along with their population sizes:

  • Raqqa province (population 944,000)
  • Dayr al-Zawr province, not including Dayr al-Zawr City (746,566)
  • Shaddadi, Markada, and al-Arish districts of Hasaka (90,095)
  • Jarabulus and Manbij districts of Aleppo (467,032)

This totals a population of 2,247,693 in Syria alone for ISIL to administer, while both imposing extreme Islamic rule and sustaining large-scale offensive operations elsewhere. For comparison, in Afghanistan it took Regional Command Southwest around 30,000 U.S., U.K. and Danish troops to attempt to subdue Helmand and Nimruz, which have a combined population of 1,598,369. Further, these coalition forces had the help of the Afghan National Army, the Afghan National Police, the Afghan Community Order Police, and the National Directorate of Security, meaning that the total forces on their side were far more than 30,000. Even accounting for terrain and infrastructural differences, and the fact that ISIL does not possess the long tail of modern Western forces (i.e., the logistics necessary to sustain a modern fighting force, technological specialists, and a vast intelligence infrastructure), ISIL would still need, at minimum, a comparable force of around 30,000 just to maintain their Syria-based holdings.

The fact that U.S. intelligence estimates of ISIL’s force size are too low becomes evident when one considers the group’s current Iraq holdings, along with their population size:

  • Mosul, Hamdaniya, Tal Afar, al-Hadar and Ba’aj districts of Ninawa (population 1,984,829, reduced to around 1,484,829 due to the reported flight of 500,000)
  • Al-Dibs, Daquq, and Hawija districts of Kirkuk (525,758)
  • Al-Qa’im, Rutba, Anah, Hit, and Falluja districts of Anbar (1,767,686, likely reduced to 1,587,686 due to the reported flight of 180,000 from Hit)
  • Al-Sharqat, Tikrit, and Dawr districts of Salahaddin (367,244)

In Iraq, that’s a population of 3,965,517 to 4,645,517 that ISIL has to control—about twice the size of the group’s Syria holdings. And these territorial holdings come on top of multiple ISIL contingents that maintain their own logistics and support personnel, and that are capable of carrying out battalion-sized offensive operations, including the al-Sarim al-Battar, al-Aqsa, Grozny, Sarajevo, Yarmuk, Jalut, Dawud, Jabal, Saiqa, Zilzal, al-Qa’qa, Hitin, and al-Qadisiyah battalions. (Note that “battalion” does not mean the same thing for ISIL as it does for U.S. forces: ISIL’s battalions are not as large.) With these factors in mind, Hisham al-Hashimi’s estimate of ISIL having 100,000 men under arms appears plausible. Further, if one takes into account ISIL’s establishment of multiple security bodies and the mass conscription it has imposed in Raqqa, Ninawa, and western Anbar, the overall Kurdish estimate of 200,000 men may be plausible as well.

In addition to ISIL’s force structure and the extent of its holdings, another indication that U.S. intelligence estimates are too low is the amount of attrition that has been inflicted upon ISIL. CENTCOM has said that it has killed 6,000 ISIL fighters in airstrikes alone since August. If the low-end estimates are accurate, then between 20-30% of ISIL’s total manpower has been eliminated by airstrikes. Such a conclusion is clearly unrealistic: Even if ISIL were able to replenish its ranks at a rate equal to the attrition, the group would be performing far worse on the battlefield if it had had to replace such a large percentage of its force in such a short period. By contrast, if you accept Hashimi’s figure of 100,000 ISIL fighters, the group has only lost about one-tenth of its total force.

It still isn’t clear precisely how many fighters ISIL has, but its total force is likely to be closer to 100,000 than to 30,000 (although, unlike the martyrdom-seeking fanatics in its ranks, ISIL’s conscripts are more likely to turn tail and run in a tough situation). The low-end estimates are simply too low to be realistic, while the high-end estimates—of which many observers are intuitively skeptical—are far more plausible than they first appear once one attempts to break them down more systematically.


Daveed Gartenstein-Ross is a senior fellow at the Foundation for Defense of Democracies (FDD) and an adjunct assistant professor in Georgetown University’s security studies program. FDD’s Oren Adaki contributed to the Arabic-language research for this article.

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25 thoughts on “How Many Fighters Does the Islamic State Really Have?

  1. When you talk about how ISIS can control such large areas containing a large population you also need to factor in their tactics.

    A smaller fighting force that shows no mercy while torturing and killing men, women and children indiscriminately has a distinct advantage when it comes to policing and controlling territory.

    Fear and terror are extremely powerful weapons.

    1. Such naivete! War is hardly about numbers: it must be about goals! Otherwise, our own ineptness will swallow us. We were fed a steady diet of numbers in Vietnam: true or false, those numbers meant nothing. There was no goal: we were totally inept at stating what we, as a nation needed to or even wanted to accomplish. Korea? same story, and moreover, we underestimated foreign involvement. NOTE: that seems to be our national pastime: in the mid-east, it is critical to manipulate the positions of the parties.
      So what of our goals:
      1. To restore an Iraqi state at any cost?
      2. To bridge the remnants of the Baathists into another demonic state of domination — to fend away the Iranians?
      3. To elevate the robust Kurds into an new power that balances Turks and Iranians and Shiia and Sunnis alike against the Syrians and even Israelis?
      4. Induce the Turks to be our puppet to rule the moslum remnants (caliphate) and protect our robber baron oil companies?
      In short, without a stated goal, wtf are we doing there? Let them kill each other as they have for centuries. The Russians seem quite eager to do just that: sell arms; let the caliphates direct the killing. How fast did the Soviets leave Afghanistan?
      5. Look at the numbers required just to administer these lands? For what? Yes, there are tens-of-millions of law abiding, genteel, peaceful persons in these areas, and they will likely continue to die at the hands of their brothers. How many American lives will you sacrifice to provide these peoples’ peace? Before you give me the worn-out phrase, remember President Wilson wanted to make the world safe for Democracy. Is it a safer place today? Without a goal and a plan to reach that goal, there can be a million Saddam Husseins: you wanta kill them all? History will record this as the Bush Wars era: one after another after another — without any meaningful gain, resulting from an inability to think and unwillingness to use diplomacy — not surrender — to advance USA’s interests: NOT the interests of Corporate America.

      1. You hit all of the salient high points but missed one. Bush left officer with both Iraq and Afghanistan relatively calm. It was not until Obama feeling a need to honor a campaign pledge left a hole in the security of Iraq. He then armed Isil as a remedy. It is clear that the naiveté’ that was argued of him in his run for president showed itself in a most horrendous form. They stated that Iraq did not want a status of forces agreement and I say pffft. We secured Iraq with money and lives to do what has been done is equally as repugnant as beginning the wars.

        1. Yes, William has a point that we must have goals if we are to advance our interests in the Middle East, but our current goal should be to do whatever it takes to defeat ISIL/ISIS and create a safe space for all moderate Muslims in Syria so that Sunni’s don’t have to choose between Shia rule or ISIS rule. Obama has no goals and no strategy and his ignorance and inexperience has cost all of humanity a very high price. William does not really know what he is talking about, however, so don’t be fooled. First, the article was more interested in shedding light on our enemy and what we are dealing with rather than trying to compare how many soldiers they have versus how many we have militarily. And I disagree with his assessment that history will record this as the Bush Wars era. Maybe he is right about that if Democrats write the history books, but the Iraq wars were obviously not about ISIS, as it had not yet formed.

          Yes, if we could have seen into the future and somehow known ahead of time that Obama was going to pull out prematurely and let Iraq descend into chaos while at the same time declaring a “red line” in Syria and then turn his back on moderate Sunni Muslims there to be mass murdered by Assad all resulting in the formation and expansion of I.S. in Syria and northern Iraq, then yes, in hind-sight Hussein does not look so bad in comparison because ISIS is even more brutal than his regime was.

          But if the historians are objective, they will write that the rise of ISIS and the resulting migration crisis in Europe (including the drownings in the Mediterranean as well as the Paris attack) was the result of Obama’s failed foreign policy, not Bush’s. Bush saw Hussein and the Baath Party in Iraq and their ambition to take over the Middle East as similar to the beginnings of Hitler and the Nazi Party in Germany and their ambition to take over Europe. Obama thinks 2 degrees of global warming over the next 50 years is a bigger threat than ISIS and would rather let the world go to hell than intervene militarily anywhere.

          I think preventing World War III before it began and trying to turn Iraq into a central location of peace, stability, democracy and an example for the rest of the Middle East to follow was a noble goal. The surge worked and we had an election. We were so close to achieving Bush’s vision: we had planted the seeds and were cultivating something that could have been strong and enduring–a good influence on Islam but Emperor Obama ripped it up by the roots and let the Iran direct the path of Iraq and the result is an entire religion being pulled towards its evil side. We should have left a presence in Iraq. Three bases there to help support and guide the Iraqi’s would have been enough, just like we still have US military bases in Germany, Japan, and South Korea–and look how those countries turned out. They are now three of the best countries in the entire world. The USA has been and can be the greatest force for good, but Obama doesn’t see America’s potential, only our flaws and he campaigned on fully withdrawing from Iraq and now we see the results of his stubbornness to do so.

  2. Not just their tactics, but also the fact that they must certainly enjoy some level of popular support in the areas they control (which is equally depressing and remarkable). It’s impossible to imagine that they could hold all of that territory without it.

    1. If you think the people of Iraq and Syria who are under the control of ISIL have “popular support” you are out of your mind. The people there live under fear of death and mutilation by this savage group every single day. They are caught between a government that has failed them and radicalized rogue militias that seek to control them.

      1. No, he is not out of his mind. If they don’t have support, they will be kicked out the land pretty fast. Every regime has some sort of support from it’s own people. Provide safety and some rules, people can follow to stay under the radar of the authorities, and most will simply comply.

        ISIS also doesn’t torture the normal population, it are the dissidents they go after. Unfortunetaly there idea of dissidents is rather broad, but that is another discussion.

  3. Control of wide swaths of rural areas, for these guys, does not mandate a constant presence ala US tactics.

    Concur with Carl; using that methodology one can control the more populous regions with a heavier force while maintaining influence over lower populated regions with fewer men.

      1. Obviously, someone is lumping all the different movements together into one IS umbrella. There are the foreign fighters in Syria that are sponsored by the US and its allies. There are the Baathists and Sunni tribes that have risen up against the Shiite government in Baghdad. There are the various criminal elements that were released from the prisons in 2012-2013 by ‘Al Qaeda’ or foreign special forces.

        If you just take Anbar, Mosul at 700,000 is about half the population after the ethnic cleansing by the Sunni insurgency. They estimate only 1,000 to 2,000 ‘IS’ holding this city. There are clearly many civilians who are in allegiance with ‘IS’ in order for them to maintain control over such a large city.

  4. “Even if ISIL were able to replenish its ranks at a rate equal to the attrition, the group would be performing far worse on the battlefield if it had had to replace such a large percentage of its force in such a short period. ”

    This would be the same IS that abandoned north, east and west of Mt Shingal without a fight, passively lost the cement plant outside Shingal, and allowed both Tal Afar and Mosul to be cut off from each other and Raqqah ?

    And then proceeded to rout in Kobane canton, allowing YPG and FSA allies to advance at 10-15km a day ?

    That certainly looks like a force thats performing less than well on battlefields.

  5. I was just about to write what Carl and others have said. Obviously that’s not necessary now, but I will say this: playing by the rules makes a force grossly inefficient when compared to one that doesn’t. IS wouldn’t need that many troops to do a massive amount of damage and exert a lot of control.

  6. You realize there is very little difference in these numbers. @00,000 sounds big but it is the numbers used by the locals. To translate you drop the last zero and devide by 2 to get the US equivilent.
    20,000/2=10,000 or about the same as the CIA estimate.

    1. Also, US-sponsored rebel force FSA is considerably smaller now. Many of the ‘moderates’ have joined ISIS, al Nusra Front, or other ‘Al Qaeda’ groups. Ambassador Ford estimates that FSA rebel number only 5,000.

  7. ISIL does not require the Logistics Tail the US Military does and that grants them an advantage when you start doing the number guessing game.

    They don’t do Ice Cream machines and movie theaters….Pizza Hut and all that kind of thing as we do when we go to War of late.

    They are about Ammo, basic food rations, spartan living conditions, and basic equipment on a much less sophisticated level than their Western adversaries.

    That is both a strength and a weakness for them.

    When going up against less dedicated and somewhat equally armed opponents they Win.

    When they, will I guess I should say….if they ever encounter US and Western Coalition Forces with all of the power we bring to the Battle Space….they lose.

    We must not under-estimate their capability or we shall certainly pay a heavy price for doing so.

    ISIL is drawing Recruits from multiple Countries and that has to be factored into the equation. A war of Attrition is not one we can win in fighting them.

    They know we are tired of War, we have a President that is not dedicated to defeating them, and we do not have a Coalition that is willing to field a Land Army to confront them.

    Until that changes….they hold the Initiative.

    We know how that works in Warfare….there are ample studies to document the side that kicks off the most engagements holds the upper hand in combat.

  8. Ralph,

    I think you are on the right track, that ISIL does not have the “tail” that Western analysts consider when fielding an army. Additionally, the free flow of fighters in and out of the battlefield makes coming up with a number nearly impossible.

    Quantifying death numbers etc do little but confuse prosecution of the war. Are you gaining ground? Are you retaking cities and are those cities peaceful?

  9. The other aspect of this conflict is that ISIL appear to have a stronger ideological basis for sustaining the war than the West. They live in a ‘false reality’ of religious fanaticism. The strength of this reality pervasive as it may be, is the belief that these fighters have nothing to lose on earth including life since that is repaid in heaven.

  10. How many are conscripts and how many are core fanatics? Think of the fanatics as being like the comissars and political officers that were scattered throughout every unit of the Red Army to both indoctrinate the men and to force them to fight with the barrel of a gun under threat of death if need be.

    Or another hypothesis would be to think of ISIS as being like a Transnational Criminal Organization (TCO). Those MS-13 Mara Salvatrucha pendejos are supposed to have 200,000 members with the majority concentrated in the Triangle of Death (El Salvador, Honduras, Guatemala) with smaller numbers in several dozen urban areas going north through Mexico on into the USA including Washington-DC according to Southern Command and the various intelligence agencies.

  11. I was looking over the numbers today and figured this out from the stats –

    Regarding our safety, Americans make up 4.6% of the world’s population but we spend more on the military than the next top 9 spending countries combined, most of which are our allies or valued trading partners. They are China, Russia, Saudi Arabia, France. United Kingdom, Germany, Japan, India, and South Korea with combined populations of 3.5+ billion meaning that American tax payers pay 90% MORE than the populations of those other countries to maintain our status.

    What are we so damn scared of that we have to throw American’s into the streets making them homeless, or cut the food stamp budget and let American’s starve? Is it the 100,000 or so ISIS members that force us into such desperation, or merely the profits of the weapons manufactures that are so precious?



    1. You think by cutting military spending we can spend more money on welfare programs and create some kind of utopia?

      First, much of the military spending goes into veterans benefits like the GI Bill, Pensions, and Veterans Healthcare. Do you seriously plan to cut funding to veterans healthcare so we can spend that money on people who have not served? Or maybe you want to cut the family housing budget and just hand out tents to the wives and children of deployed soldiers!

      Of the entire defense budget the sections that seem the most easily cut would be Research at $64 billion and Procurement at $90 billion. Research has delivered some great things in the past such as “the internet”, and procurement is essential for keeping our forces battle ready. I don’t want to see what the world would be like if we were suddenly on the same level as Russian and China. Frankly, being 10 years ahead is what keeps them in check at the moment.

      What benefit do we get from welfare? A permanent underclasses and rampant slums! Short term unemployment benefits and worker retraining is worthwhile. Even provided unlimited resources the government could not fix our homeless problem. If you want to solve the homeless issue… get off your butt and do it! I bought a homeless couple a meal and a tent. I also convinced the owner of a Subway to provide them free meals. We don’t need bureaucrats to fix this, we need private citizens doing their part. It will create a better society and a better world!

  12. When the size and disposition of an enemy force is unknown, you must start at the fundamental level of analysis and collect information that answers size, composition, and disposition questions. A military tactical and operational approach is a good basis to start. Fuad Hussein, noted in the article, briefly laid out a possible doctrinal template for tactical and operation levels of the Daesh force strength. Consider the territory or from a military viewpoint what is the area of operations and area of interest. Daesh forces will likely in some echelon or numbers be found in both areas defined. Controlled population size will have a doctrinal influence on the Daesh strength size also. These are basis or baselines to start figuring out the enemy size (echelons), strength, and disposition on the ground. Next, start asking questions such as how long does it take for information to flow from location to location that Daesh occupy, how many layers seem to handle the information, who issues orders, what are sources of finance and material(many of the Daesh now show up in uniform); answering questions such as these fill in gaps and begin to confirm doctrinal template assumptions and facts. When the doctrinal template information is applied to the environment and geography a situation template begins to come clear. The entire process is fundamental to Information Analysis and Collection. Guess work and ad hoc numbers are the products of amateurs.

  13. It is not difficult for US and Europe to defeat ISIS completely in a week by airstrikes, like they did in Iraq and Libiya. But Obama’s thoughtless policies have made US a laughing stock in world. ISIS country is not Afghanistan like hilly terrain ( easy to hide). ISIS are sitting duck but US needs strong leader like Bush. Obama has now abandoned his his big talk of destroying the chemical weapons of Syria because of ear of ISIS.Syria must be laughing secretly.

  14. Knowing the numbers is part of the challenge. Next questions are:

    1) what is their motivation for fighting and what are the strategic and tactical implications of these motivations. A high willed force can overcome a larger less motivated force, as the Iraqi Security Forces have learned.

    2) what are the individual and collective skills of their fighters? Are they able to translate their numbers and willpower into effective battlefield maneuvers. And, if so, what are they capable of doing—infantry combat at the squad level, battalion level, etc?

    3) what is their relative military effectiveness compared to their adversaries and how will that effectiveness vary across time and space.

    In many ways, however, these questions are unknowable. Their size and capabilities are constantly in flux. The group itself probably doesn’t even know its exact capabilities at any given time.