Rotation Needs?

UPDATE: Ok, it is 9 MAY 07 and I am just revising this post. I originally assumed 20 brigades overseas, then updated it yesterday to assume 23 when I read we have 20 brigades in Iraq alone, then came back to revise when I read we have 2 brigades in Afghanistan and not 3, and also noted a pretty bad math error.

So let me try to redeem myself with a complete rewrite and an apology for totally bollixing up the post. I'm just going to revise the numbers and conclusion with the basic post structure. Bad week to give up sniffing glue is all I'm going to say. Anyway, revised:

When the Department of Defense announced fifteen month tours of duty for active Army units, I took the military's word that they needed to do this because of lack of numbers to support 22 brigades in the field, is the number of brigades we have deployed in Afghanistan (2) and Iraq (20).

Yet I was puzzled since I didn't think we needed to do this to support this level of commitment. I didn't express this yet noted that I hoped the real reason was to demonstrate our commitment to doing what was necessary to win in Iraq.

Yet shortly after that, I read that it was really part of the Army's attempt to leverage more end strength.

So let me go back to my first assumption that I perhaps too easily abandoned, that we have enough troops for one-year tours. I'm going from memory on the following numbers, so bear with me.

Assume 38 active Army brigades. Plus 9 Marine regimental combat teams. That's 47 brigade equivalents in the active component.

Subtract one Army brigade in South Korea that isn't available. Subtract two Marine regiments to support 2 or 3 MEUs afloat at any one time outside of Iraq and Afghanistan. So we have 44 brigades.

But with overlaps and transit time, we need more than one brigade to support a brigade in the field for a year. I think the multiplier is 1.15.

So to keep 22 brigades in the field (with one year at home), we need 44 brigades X 1.15 for a total of 50.6 brigades--call it 51.

This is seven brigades more than we have in our active components available for supporting a rotation. We do have reserve Army and Marine units, but it is hardly reasonable to assume the equivalent of seven brigades from the reserves each year. In time we plan to make 4-5 Army National Guard brigades available each year when the Guard is reorganized as an operational reserve. Plus there are three reserve Marine regiments to tag. But even in this future ideal this is not enough to bridge the current gap.

Plus, we are adding active brigades each year for the next several years. But again, this will take several years to add a half dozen brigades or so that could bridge this gap.

We can effectively--in the short run--multiply our active Army brigades by 1.25 by assigning them to 15-month tours. Do we really need 53 yearly brigade-equivalents (using 37 Army brigades and 7 Marine regiments available) to support 22 brigades in the field? This 15-month tour just applies to active Army brigades, so I'm just adjusting the Army numbers up doing back-of-the-envelope calculations here. Since we need the equivalent of 51 brigades to support 22 brigades in the field, and the tour extension gives us "53," my answer is yes indeed, we did need to do this.

And unlike my original post speculation, this does not in theory free up five brigades for use elsewhere--like Iran--in an emergency, without affecting the Iraq and Afghanistan campaigns. I have almost given up on the idea that the President and Prime Minister Blair will take down the mullahs. But this tour extension is not necessarily the proof that we will strike Iran, unless we don't really need the five extra brigades for the purspose of the surge. I thought a couple would do with the main impact being a change in strategy.

Still, the idea that this is bureaucratic maneuvering doesn't appear to hold up. My amateur number crunching does indicate that we need 15-month tours of duty for the current commitments.

In a couple years we'll perhaps have enough additional active component forces to provide this rotation--but not quite yet. Even in a year, if we assume we can shake loose a couple National Guard brigades per year, we might have enough active Army and Marine units to allow the Army to drop back to 12-month tours if the goal is simply to support Iraq and Afghanistan at current levels.

And of course, I don't think this level of commitment will be sustained beyond 2008 for domestic political reasons alone so discussing how we'd hold on until new units are made available is fairly pointless.

So I'll backtrack on my assertion that we clearly don't need to increase Army tours to fifteen months. It's a little beyond the edge of being doable and caution is in order.