The secretary gave a very complete rundown. The math is fairly straightforward. Just take one segment, the ground combat brigades. We have 20 ground combat brigades in Iraq. You have 3 in Afghanistan. That's 23. You've got an inventory that has currently 38 Army brigades -- building to 48, but 38 available today, and 9 -- correction, 8 Marine regimental combat teams -- building to 9, but 8 available,today.
So between the Army and the Marine Corps, we have the equivalent of 46 brigades. You're using 23 at a time right now, which puts you automatically into a port-and-starboard 12 months on, 12 months off, even before you start having overlap of turnover and before you count the brigade that's in Korea and the brigade that's in Kosovo, which is why we went to 15 and 12 for the Army and 7 and 6 for the Marine Corps, as far as deployment time. So those numbers, and that's just one example, are managed very carefully and very closely. And anything that puts further strictures or criteria on when and how to use ends up with the impact that the secretary -- what the secretary mentioned.
I didn't know that we had a brigade combat team in Kosovo. I thought we had odds and sods that wouldn't impact the brigade-based rotations. And maybe I'm right to do this since Pace doesn't also count the Kosovo force as part of the rotatons needs he cites. I also thought we have just 2 brigades in Afghansitan. (I think I keep rediscovering this fact for some reason.)
At the other end, I had assumed we had 41 Army brigades by now, but also assumed some Marine regiments would be excluded to support MEU rotations at sea, so we'd only have 6 to use for rotations.
So the total number is still about what I've assumed. Also, I know the Marines are on tours of 7 months in and 7 months off, but that is still 1:1.
Assuming one year on and one year off, start with 46 brigades. By subtracting the Kosovo and South Korea brigades, plus assuming rotation overlap, take those 44 brigades and divide by two. So we have 22 brigades for each year of deployment with another 22 at home resting and preparing to go back. Then multiply these 22 actual brigades by 0.87, to account for overlap since one brigade doesn't arrive at midnight just as the existing unit departs for home. And the units have travel time, too. This gives you the number of brigades we can put in the field at one time (I call them brigade-year-equivalents here). This is only 19. Four fewer than the 23 we have in combat in Iraq and Afghanistan.
So you can see that to support 20 brigades in Iraq and 3 in Afghanistan we had to go to 15-month tours which essentially multiplies your brigade equivalents (in the short run, until stress has an effect) by 25%. Multiply the 22 available brigades by 1.25 to get 27.5 brigade equivalents. Multiply 27.5 by 0.87 and you get 24 brigade-year-equivalents (well, 23.925). So we have 24 brigade-year-equivalents at 15-month tours to support the need for 23 brigades in the field for a year. You could edge this down a bit since the Marines don't have extended tours, but they have only 2 of the total brigades in the field. And this is done assuming only active forces.
Remember, we've alerted 4 (or is it 5?) National Guard brigades. If deployed, these will serve only 9 months in the field under current restrictions, so that is just 3 or 4 brigade equivalents (counting them as 75% of a unit serving a full year). If we go back to 12-month tours for the active Army, we could still just about support the surge a little longer.
These are the numbers on why we can support the surge right now. And why we could extend it to near the end of 2008 if conditions require it, as Petraeus noted.
In time, we will add 10 more Army brigades to the active force and another Marine regimental combat team. Ideally, long before this expansion, we should be pulling back from combat and pulling brigades out of Iraq. And then I guess we see if the Pentagon is right about worrying whether Congress will fully fund a larger military ground force once it is not in combat. that number matters, too, as to whether we will develop a hollow military.
The numbers on troop rotations also show why it is a tremendous challenge for the military to keep units in the field and why any Congressional meddling in deployment rules could seriously throw our calculations out of whack. To be fair to the assessment of the brainpower of Congress, that is exactly what Congress wants to do and not merely a matter of ignorance.
