Let's say that there's a 2-million-year-old impact crater where the Strait of Gibraltar used to be, and that there's an impact peak or a series of impact peaks in the middle that are far enough above the water to be used as ports/forts/etc.
However, consider that this crater is a product of a meteor impact. Does this add any other reasons for a country to want to hold these islands, besides the fact that they're strategic chokepoints? (whoever controls the islands controls the nearby waters)
the meteor brought a large quantity of natural resources to the area, and mining them is significantly easier (more of a modern thing, given that a lot of it would be underwater)
salt deposits being pushed up the sides of the crater by the blast wave (more of a pre-industrial thing; for instance, salt was very valuable back then)
impactite being used as a valuable commodity
coral reefs growing around the impact mountains, meaning everything from tourism to pearl harvesting