Despite the success with a new Iraqi government, elections, a new Constitution etc. The country is still highly unstable and fighting and terrorist attacks occur on a regular basis. Despite continuous fighting and combat, pacification seems to be a long way off at this point and it doesn't seem as if things are likely to improve soon.
Another disadvantage is related to the forces needed for such an action. According to estimates, a force of around 350,000 to 500,000 is needed for a potential success of a pacification action through force. The U.S. And the coalition forces have less than 200,000 people in the field and the pressure is already extremely high to reduce those numbers rather than further increase them. The political and public opinion pressure in the U.S. would be tremendous if the government was to think about increasing the number of troops stationed in Iraq. It just seems improbable that the U.S. And the coalition forces would actually have the potential to be able to put in practice a decision that would involve pacification through force.
Backing a potential winner among the factions is another solution of the U.S. government. The problem with the current state of affairs is that the U.S. troops seem to be fighting all factions involved in the war. A solution such as the one proposed would actually bring local allies to the U.S. forces and might help end the conflict a lot sooner than otherwise.
However, this solution has several disadvantages. First of all, the U.S. wants to achieve a peaceful and unified Iraq and this solution would not guarantee either of these states. It would not guarantee the factions would actually stop fighting one another, especially the factions that would perceive as having lost the conflict. It would not provide a unified Iraq either, because it would not encourage real collaboration between the victor faction and the remaining ones. Additionally, the solution does not seem feasible.
Finally, the last solution, currently in practice in Iraq, involves attempting to militarily support the elected government, while at the same time fighting the insurgents and terrorist groups and attempting to "broker" a deal. The problem with this solution is that it lacks finality. Indeed, this is what the U.S. has proposed from 2003 (similar to using force to pacify the country) and, despite some political successes, in many cases, the situation has not changed much during this period of time. A great disadvantage of this solution is that it can actually go on indefinitely and that it doesn't provide an exit strategy in case things don't actually work out. Additionally, the question that arises is when is the government perceived as being sufficiently strong to rule over the country without the U.S. help? How long does it need the U.S. army's support and when can one say that a deal has been successfully completed between all the factions within the country?
As we can see from the solutions proposed, each has important disadvantages, notably more disadvantages than advantages, and it seems, at this point, that there is no clear optimal solution that can be implemented in Iraq. The situation is not only complicated because of the way things look in the country (although that is highly challenging), but also because of the pressures in the U.S. To end the war (or continue it, depending on the faction here), as well as the numerous implications the conflict has in the entire Middle East. In fact, each solution and its implementation would most likely bring in foreign players as well, such as Israel or Iran, each backing up or fighting one solution or another. A final solution can only be reached by taking into consideration regional implication along with internal issues.
Finally, the U.S. presidential campaign in 2008 might also be important towards the final decision to be made, depending on the stance of each of the two candidates.
1. Oliker, Olga; Crane, Keith. U.S. Policy Options for Iraq. For U.S. Air Force. 2007.
Oliker, Olga; Crane, Keith. U.S. Policy Options for Iraq. For U.S. Air Force. 2007.