The day in which unmanned "ghost ships" ply the seas laden with cargo is fast approaching. But don't expect the drone vessels to be flying a U.S. flag.

The United States is not among the global hotspots where a revolution in autonomous commercial shipping is unfolding. One needs to look to places like Norway, Finland, Singapore and China to observe the competition for unmanned shipping.

A shipyard in Norway will soon begin building a 237-foot battery-powered electric container ship that will operate with nary a sailor aboard by 2020.

Announcement of that project and several others over the past year have rippled through maritime circles worldwide.

Finland is looking at prototypes for an autonomous ferry. China has set aside a 225-square-mile ocean area to test crewless ships. And Japanese shipping lines have formed a consortium with the goal of having 250 remote-control cargo ships by 2025.