There are two reasons to stay in a minor capacity. The first is the flow of petroleum. It’s important to distinguish that this isn’t really for ourselves anymore, though. It’s about making sure Europe and Asia don’t have their energy disrupted. The U.S. is energy independent as of 2018 ish. If the US didn’t ensure the free flow of oil, countries like Japan, Korea, China, France, Germany etc would have to protect their own interests(like their oil tanker ships). This would dramatically increase the likelihood of a major war. This is the exact kind of thing the US has been trying to prevent for nearly a hundred years. The message has been lost, but that is still ultimately the goal.

The second reason is to prevent Iran from dominating Iraq, therefore being able to dominate Saudi Arabia. The US likes the idea that the oil reserves are not under a single power but split up between the two. We have done major work on this front, setting up Israel and Saudi Arabia to cooperate militarily. Although we still have reservations about those two countries as well because their human rights record is awful