WASHINGTON: The US Navy believes it has finally worked out the solution to a problem that has intrigued scientists for decades: how to take seawater and use it as fuel. The development of a liquid hydrocarbon fuel is being hailed as "a game-changer" because it would signficantly shorten the supply chain, a weak link that makes any force easier to attack. The US has a fleet of 15 military oil tankers, and only aircraft carriers and some submarines are equipped with nuclear propulsion. All other vessels must frequently abandon their mission for a few hours to navigate in parallel with...