So, is it 25,000?

I hate to keep harping on this…..but I do believe in reasonable estimates of opposing forces strength and losses. I am not sure we are doing that.

1. The U.S. claimed in August that there were 19,000 – 25,000 ISIL:Islamic State strength estimates
   1. I don’t believe I have seen strength estimates from before this time that is more than 25,000: Global Security
   2. About half were in Iraq.
2. The U.S. now claims there are 12,000 to 15,000 ISIL: white-house-isis-down-to-12000-15000-battle-ready-fighters
   1. This includes 3,000 to 5,000 in Mosul: War updates
3. The U.S. claims were have killed 50,000 in the last two years: Over 50000 killed
   1. Including 25,000 in the last 11 months: pentagon-counts-isil-dead-refuses-discuss-them
   2. 25,000 – 50,000 = 15,000…meaning they recruited 40,000 new fighters in the last two years?
4. The U.S. claims were have attrited 75% of ISIL: US-Officials-Say-ISIS-Has-12-000
   1. 15,00 times 4 = 60,000…meaning working backwards this was the ISIL strength….or this includes the 40,000 new recruits added to a strength originally equal to 25,000? This math actually works, if you accept the figure of 40,000 new recruits.
   2. Of course, this is exterminating and replacing the entire ISIL force each year for two years in a row. Can’t really recall the historical president for this.
5. The UK estimates we have killed 25,000 ISIL: uk-us-number-isis-fighters-killed
   1. This seems more reasonable.

Of course, part of the problem is that ISIL and every other insurgency movement out there does not consists only of full-time fighters. For example (see America’s Modern Wars: Chapter 11: “Estimating Insurgent Force Size”), looking at some the insurgent strength estimates from Vietnam, Cabanas (Mexico) and Shining Path (Peru), we came up with some rules of thumb for determining the mix of insurgents (see page 120):

1. Full-time insurgents make up 10 to 20% of the force.
2. Full-time and part-time insurgents are 20 to 50% of the force.
3. Casual insurgents are 40 to 80% of the force.

This was based on a very limited selection of marginal data and of course, may not be relevant to ISIL, as they have developed a more conventional-like force structure. But, it does bring up the issue that most insurgencies are not only full-time committed fighters, but lots of people that only sometimes active (often regional), and a large collection of people that are only occasionally active (and may become inactive if things are not going well). Also, many of the insurgents are “support personnel” vice fighters. It is an issue that I don’t believe I have seen anyone else attempt to deal with analytically. Our efforts were only preliminary.