TYB
Sauce
https://www.thedrive.com/the-war-zone/14309/why-the-navys-top-spy-submarine-flew-a-pirate-flag-while-pulling-into-port
https://www.thedrive.com/the-war-zone/14309/why-the-navys-top-spy-submarine-flew-a-pirate-flag-while-pulling-into-port
The Jimmy Carter's iteration of the flag uses the crossed swords instead of the crossed bones. This could reflect the vessel's "cloak and dagger" secret mission set or it could be just what was available when the flag was procured.