Steven Den Beste (repeatedly), Donald Sensing and Tacitus have all noted how overcommitted the military is currently, particularly in low-density high-demand forces (MPs, SOF, Civil Affairs and the like) and heavy ground forces. We built our force around two theater commitments, plus minor operations, and now we have them in spades. We have a major occupation in Iraq, minor occupations in Afghanistan and the Balkans, and a requirement for contingency reserves for Korea in case the North acts up. We most likely will rotate some of the Korean reserves into Iraq later in the year (particularly 1Cav and 25Inf are good candidates) replacing 3ID and later 1AD or 4ID.
But then what? The truth is, we are going to need one to two full divisions in Iraq for the next five years at least, and we'll need more than that until we can get an Iraqi police force and army off the ground. For the next two years at least, while we're building Iraqi institutions, we'll need three to four divisions in Iraq. We have commitments for another two to three divisions worth of troops in various hotspots, and another two to three divisions to reinforce Korea. Then we're out of troops, and we don't have any more to spread around.
We do have additional commitments to take care of, though. We will possibly fight in one or all of Syria, Iran and Korea in the next three to five years. It is almost a certainty that we will fight in one of those countries. (I expect it to be Syria. Iran and North Korea can be resolved short of war.) In addition to that, there is a possibility of us needing to commit some forces to Africa. And who knows what might crop up that we can't anticipate from the current world situation?
But we do have options. One that I don't hear being bandied about much, though it's been mentioned a few times, is raising new active duty divisions and special-purpose troops. This would certainly be expensive. In fact, it would require either significant spending cuts, or significant tax increases (more than reversing the last three years' cuts) or perhaps some of both. I do not believe that there would be a shortage of people willing to volunteer or to stay in, so that no draft would be needed, provided that they would not have to maintain today's high optempo for an indefinite period of time. This option would also take significant time as well. The good part, though, is that it would fix the problem, and during this time of economic uncertainty, it would be a far better expenditure of government money than most of the ways the government tries to boost employment.
Another option would be to make the strategic decision that Korea is no longer our problem. After all, it is not as if South Korea cannot defend itself. In the absence of the Cold War reasons for being in Korea, we could easily back out of that commitment. That alone would fix a huge amount of our force structure problems, though we would have to be very careful to avoid the appearance of just abandoning South Korea.
It's possible that regional organizations like OSCE or OAS could create regional forces, along with the support units to deploy and support them. Using the UN of course would lend the pretense of legitimacy, though the UN has proven a totally incompetent intervenor in a crisis. I just don't see it happening, though. While lots of countries like the theory of international intervention to prevent disasters, the Congo is a good example of why this kind of intervention doesn't typically work. Basically, you can't wage war by committee.
I really don't see us activating the Guard and Reserve. Let's face it, that would be problematic in the extreme. While we could do it (and would if we had to), the economic disruption of activing a unit like 49AD (from my home State of Texas) would be immense. The political problems would be huge, as well, though I believe they would be surmountable. I suspect that 10 years or so down the road, when the active part of the war on terror is over, we'll transition more heavy forces into the Guard and Reserve, and put more light and medium forces in the active duty Army.
Another way we could bridge the gap would be to create a sort of permanent coalition of the willing. The idea would be to create an organization of liberal democracies, with its own armed forces not subject to direct control of any nation, but with strong national controls to prevent rash use of those forces. In particular, the mission of this organization would be limited to fighting terrorism and nation building. This needs its own post, because the idea needs a lot of explaining and cautions, but if such an organization existed (basically a UN with a far more limited mission, but real teeth to carry it out, and a far more exclusive membership), it would free up a lot of the US forces for use elsewhere. The trick would be to avoid the problems (mostly philosophical) that prevent the UN from being in any way useful in a crisis).
In any case, it's clear we have to do something, and I hope that President Bush makes clear soon what that is to be.