The Skyhook system was developed by British Aerospace, involving the use of a crane with a top mating mechanism hung over the sea to catch and release VTOL aircraft, such as the Harrier Jump Jet. The system could be installed on ships of various configurations and sizes, even those as small as frigates, enabling virtually any Royal Navy ship to deploy a handful of Harriers. It was intended for the Skyhook to enable not only the launch and recovery of such aircraft, but to enable rapid rearming and refuelling operations to be performed. The system was marketed to various foreign customers into the 1990s, such as to enable Japan's fleet of helicopter destroyers to operate Harriers by installing the Skyhook onboard. Perhaps the most elaborate implementation proposed was the application of the Skyhook to large submarines, such as the Russian , to produce a submarine aircraft carrier.