Written by Ben Ho.

Japan’s controversial Izumo-class helicopter destroyers have been under the spotlight recently. Last month, the ruling Liberal Democratic Party suggested converting the platform to an aircraft carrier that can deploy the F-35B Lightning vertical short take-off and landing strike fighter. This came after former Maritime Self-Defense Force (MSDF) senior executives told the Asahi Shimbun newspaper that the Izumos were designed from the start to operate tactical jets so as to counter China’s possible aggrandisement in the East China Sea.

There has been much talk about this issue in the defence community. One commentator described F-35B-armed Izumos as “potentially formidable strike carriers”. Another went as far as to say the Izumo-class aircraft carriers would herald “a new era of power projection for Japan the likes of which the world has not seen since the end of World War II”. Viewed in isolation, such arguments have an element of truth to them as the Lightning is a fifth-generation fighter with ultra-modern capabilities. However, a closer study of the matter would show that an Izumo aircraft carrier is hardly the world-beating combat platform some have made them out to be because of its possibly miniscule air wing, as well as the challenging operating environment it is likely to be deployed in.

Limited organic airpower

The raison d’être of the carrier is its aircraft complement, and the latter’s size dictates the operations the vessel can execute. With a displacement of 27,000 tons and a potential air wing of about a dozen F-35Bs, the Izumo flat-top would be classified as a “small-deck” carrier and must grapple with the conundrum such a vessel invariably faces. Simply put, this dilemma revolves around what proportion of a carrier’s airpower should be devoted to defence and to attack. Allocate more fighters to strike missions, and the carrier force’s susceptibility to threats increases; conversely, set aside more aircraft for force protection, and the flat-top’s ability to project power declines.

The challenge thus is for the Japanese carrier force commander to strike a judicious balance between attack and defence. Bearing in mind the Izumo’s capital-ship status and hefty price tag (it has a unit cost of $1.2 billion and the cost of refitting it as a carrier will incur another hundreds of million dollars), its protection from enemy threats would be critical. Hence, a large proportion of the ship’s aircraft complement would invariably be dedicated to this. But with an air wing of barely a dozen Lightnings – an airplane with well-documented reliability issues – force protection in the face of long-range precision fires would be a trying task, let alone power projection. As one defence writer puts it: “Would Japan really risk the lives of a thousand sailors just to put 10 F-35s in the air?”

While an Izumo-class platform capable of operating fixed-wing aircraft is of rather limited usefulness during a conflict with a peer enemy like China, the same cannot be said of it during peacetime.

Indeed, the converted Izumo would suffer from the small-deck carrier conundrum to a much greater extent compared to its Chinese counterparts given that the fighter complements of the Liaoning and Type 001A are twice as large. Seen in this light, the Japanese carrier is hardly the game-changer that some commentators have asserted it could be.

Challenging operating environment

The Izumo’s “small-deck carrier quandary” would be exacerbated by the dangerous battlespace it is likely to operate in – the East China Sea (or more specifically the Senkakus/Diaoyus), which is well within the Chinese anti-access/area-denial envelope. An MSDF executive told the Asahi Shimbun that “the plan to construct the Izumo was settled with its future conversion in mind to prepare for any possible contingency of the unavailability of the ASDF Naha base”. He was referring to the major Japanese Air Self-Defense Force base at the capital of Okinawa prefecture, which is likely to be targeted should hostilities with a potential adversary like China break out.

While Washington has pledged support for Tokyo during a Senkakus conflict, it is not a given that U.S. carrier strike groups would be deployed during such an eventuality.

That said, without  the protective cover of American naval airpower, an Izumo carrier force operating near the Senkakus would essentially be on its own should Naha or other friendly bases in the Ryukyus be taken out of action.

The esteemed naval scholar James Holmes once said that “(g)eography may not be key, but it molds destiny” and that “a Senkakus conflict is probably the hardest case” the Japanese military would face. A look at the map of the region shows the remoteness of the disputed isles in relation to friendly forces. Land-based airpower from mainland Japan is simply too far away to provide sustained and effective cover for any Izumo task force in the Senkaku littoral. And even if friendly bases in the Ryukyus are operable, they are still a few hundred kilometres away from the area of operations, and the operational challenges which shore-based planes face in protecting maritime interests are legion. These challenges include “lesser time on task”, lower pilot efficiency, as well as difficulties in coordinating operations between terrestrial and sea forces.

Whither Japan’s starter carrier?

All in all, while an Izumo-class platform capable of operating fixed-wing aircraft is of rather limited usefulness during a conflict with a peer enemy like China, the same cannot be said of it during peacetime. Indeed, a “full-fledged” carrier is highly suited for the traditional naval role of showing the flag. Moreover, the cutting-edge sensors of the F-35B would stand the Izumo in very good stead in handling the increasingly prevalent grey-zone situations where surveillance and domain awareness capabilities are crucial.

In the final analysis, an Izumo flat-top would be highly reminiscent of HIJMS Hosho of World War Two fame (or ignominy if you will). Japan’s first purpose-built flat-top saw no major action during the conflict because of its small size (7,500 tons displacement) and concomitant limited organic airpower (20-strong air group). In comparison, most light carriers of the Second World War were around 10,000 tons in size and deployed about 30 planes. Nevertheless, the Hosho served as a useful training platform for carrier operations during the war, as it had done so pre-1941.

It is also noteworthy that the experiences and lessons learnt from operating the ship were valuable in the development of Japanese naval aviation before the Second World War.

Perhaps, then, an Izumo capable of handling tactical aircraft could assume the “Hosho role” for the Japanese Maritime Self-Defense Force just as the Liaoning is presumably doing for the Chinese navy. The modified Izumo could serve as a “starter carrier” for Japan to regain the institutional knowledge of operating flat-tops that has arguably been lost since the demise of the imperial navy in 1944. And should the regional strategic order deteriorate so gravely that Article 9 of the Japanese constitution has to be profoundly interpreted, Tokyo would have in place the foundations for the establishment of the 21^st-century incarnation of Kido Butai.

Ben Ho Wan Beng is a Senior Analyst with the Military Studies Programme at Singapore’s S. Rajaratnam School of International Studies. Image credit: CC by U.S. Pacific Fleet/Flickr.