[martinpw]

A counter-argument:

The military presence to protect oil supplies is not just to protect US supplies. Even before self sufficiency, the US did not import much oil from the middle east - 5x more came from Canada than all the Persian Gulf for example: https://www.eia.gov/tools/faqs/faq.php?id=727

The reason is to protect world supplies, not just US supplies. A cutoff in gulf supplies would have a huge impact on world oil prices and hence economies, and would also impact US oil prices since oil is a (mostly) fungible commodity. So there are still self-interest reasons to maintain a presence even if the country is self sufficient in oil.