IF IT’S as big as an aircraft-carrier and looks like an aircraft-carrier, chances are that it is an aircraft-carrier—or can readily be turned into one. In Yokohama on August 6th Japan unveiled its biggest warship since the second world war. Officially, the Izumo is a destroyer; when it enters service in 2015 it will come with a complement of up to 14 helicopters that will be used for anti-submarine warfare and border-surveillance missions. The ship, with a displacement of 27,000 tonnes fully loaded, is half as big again as anything else in the Japanese fleet. It will also be able to ferry lots of people and equipment to disaster-relief sites.

For the moment, at least, the Izumo does nothing to challenge Japan’s pacifist constitution, drawn up after the war, which forbids the country to project force abroad—with strike carriers, for instance. However, speculation is rife that the Izumo, with a flight deck of 248 metres (814 feet), could be used to launch fixed-wing aircraft, should the constitution or circumstances change. The vessel is similar in size to the French and Italian carriers, the Charles de Gaulle and the Cavour. It is nearly 40 metres longer than the Invincible-class carriers from which Britain operated Harrier jump-jets. Although the Izumo lacks “cats and traps” (catapults for take-off, arrester cables for landing) or a “ski-jump” bow, it would not take much modification to fly the short take-off version of America’s stealthy new Joint Strike Fighter. The Chinese, who already have a (converted Soviet) carrier and are building at least two more of a similar design, have angrily called the Izumo an “aircraft-carrier in disguise”. They have a point.