Fred Kagan seeks to explain away the differences between his earlier surge-advocacy and the Bush surge he got. There are a couple of twists and turns, but it finally comes down to this:
Brigade sizes range based on the type of unit, but average around 3,500 soldiers each. The administration’s figures are based on that estimate.
In reality, the U.S. Army does not simply deploy brigades into combat, but instead sends Brigade Combat Teams (BCTs). A BCT includes a brigade as described above, but also additional support elements such as engineers, military police, additional logistics elements, and so on, which are necessary to the functioning of the brigade in combat. In a counter-insurgency operation such as Iraq, these additional forces are fully as important to the overall success of the mission as the combat troops. Sizes of BCTs also vary, of course, but they average more like 5,000 soldiers. Since these are the formations that will actually be deployed to Iraq and used there, I have been estimating deployments on this basis: five brigade combat teams include around 25,000 soldiers; one Marine Regimental Combat Team (RCTs are somewhat smaller than Army brigades) includes perhaps 4,000. So the surge being briefed by the Bush administration now is much more likely to be around 29,000 troops than 22,000–in other words, close to the number of combat troops the IPG recommended, and, when necessary support troops are added, close to the overall numbers I had estimated before the IPG met.
In short, Kagan says we can like the surge because Bush is lying when he says it’s a surge of 22,000 troops.