Iran's seizure of an Iraqi oil well is a classical strategic probe. Iran is telling us that they think they see an opportunity now that Obama is president but they are uncertain of how big it is. A small test is required to test their boundaries and our resolve.
History teaches us that we can only find out so much information about our opponents at a distance (2.1.1 Information Limits). We are forced to make our judgments about whether or not they are leaving an opportunity open for us by what we see on the surface (4.5 Surface Characteristics).
We cannot know our boundaries unless we take actions to test them. If we think we see such an opportunity, we must test it at some point by taking action (5.2 Opportunity Exploration). However, since action is costly and mistakes can be deadly, we want to start with the smallest possible actions to minimize losses (5.4 Minimizing Action). This is exactly what.
If Iran wasn't interest in expansion in some form, this move would be unnecessary, but since that is the only way they can take the pressure off their internal problems, this little invasion was a necessary first step. What happens after this all depends on how we respond. A s Sun Tzu says:
"You must use the philosophy of an invader."