As a group of islands, it is helpful to have a military base there especially one that is related to water like the Navy. Due to it famous name, Pearl Harbor, everyone knows that there is a military base there. Having the military base there, the military officials who live on Hawaii and are part of the US Navy have jobs to coordinate the Navy and the ships.
It depends upon their jobs about how they help the military. Pearl Harbor has a great view of the harbor and helps bring and maintain the submarines and ships. They can help bring in the boats because of their services with the docks. They also help maintain these ships and make sure they are running right.