On August 6 last week the JMSDF unveiled its new helicopter “destroyer,” the Izumo (22DDH). While much media and diplomatic fuss has been made about this being an “aircraft carrier in disguise” with potentially “offensive” applications, there are some legal, practical, and future considerations that need to be understood for a balanced discussion of its significance to take place.
Following on from the discussion on Japan’s constitutional restrictions in the previous instalment of this series, the question that one should reflect upon is whether the Izumo could be regarded as constitutionally-prohibited “war potential,” given that many regard aircraft carriers to be exclusively offensive in nature. The Izumo, and the Hyuga and its sister ship, the Ise, very well could have been considered “war potential” in the early 1960s (for example) when China had no naval capabilities to speak of, and the USSR had yet to strengthen its Pacific Fleet. However, with the blue water modernization of both the USSR/Russian and Chinese navies since 1965 and 1985 respectively, there are significant geostrategic and maritime concerns that expose Japan’s security in the north and the south, making the capability to transport helicopters for Anti-Submarine Warfare in particular essential.
If we look into things a little deeper, then it becomes clear that it is not war potential, and further, contrary to various media claims, it was clearly not designed specifically for the purpose of carrying fixed-wing aircraft. Even if we do not take at face value the MSDF and Japanese government’s claims that they will not use the ship as an aircraft carrier, there are significant practical limitations regarding the Izumo playing a role as a carrier of fixed-wing aircraft. Given the size of the Izumo, it could only realistically function as what is known as a “STOVL” carrier, rather than the generally larger CATOBAR and STOBAR carriers fielded by the Americans and Russians (among others), and now the Chinese. If you are uninterested in these distinctions, essentially this means the only aircraft that can realistically be launched or recovered by the Izumo are those with Short Take-off Vertical Landing (STOVL) capabilities. These “jump jets” do not need a steam catapult or ski-jump to assist in the launch of an aircraft, or arresting gear to recover the aircraft.
This is the first problem. The SDF does not own any such planes, and at this point has no plans to acquire them. There is of course one plane that could play this role, the F-35B, which the media has automatically assumed will one day make an appearance on the Izumo. However, Japan has not yet purchased the F-35B, committed to a purchase,  and may not be able to afford to. Anyone who proposed as a policy option, and/or signed off on purchasing an “aircraft carrier” (for $1.2 billion) like the Izumo for the specific purpose of it launching jump jets that may not materialize, would deserve some kind of award for idiocy given the uncertainty about whether Japan will in the next decade even have planes it could use on such a vessel.
Even if Japan was to acquire the F-35B, a second problem arises in that while the F-35B wouldn’t necessarily “need” a ski-jump to operate off the Izumo, a ski-jump not being attached does limit the F-35B somewhat in terms of the fuel and armaments that can be carried by any given fighter (particularly important for offensive “strike” missions). A ski-jump would also allow less precious fuel to be expended in the take-off phase.  A third problem arises in that the Izumo does not have the specialized Thermion-coated landing pads that the US Marines’ Wasp amphibious ships have/will have to accommodate the F-35B, given the immense thrust and heat generated by the F-35B when coming in for a vertical landing.
So, the Izumo has no ski-jump, no specialized landing pads, no angled flight-deck allowing for simultaneous launch and recovery missions, the SDF has no F-35Bs, and the Izumo is too small to accommodate more than a handful of F-35Bs anyway. As an “offensive” aircraft carrier, it is a little weak. There is also the not-so-small problem of Japan not having any pilots capable of landing the as yet non-existent aircraft on any kind of carrier. It may well be that the stated intended uses are the actual intended uses: for Anti-Submarine Warfare (see the ISR integration with the Soryu submarines), Humanitarian Assistance and Disaster Relief at home (see the Hyuga-class ships’ role in disaster relief after 3/11), and abroad (see the other controversial ship with a through-deck, the Oosumi, in post-tsunami Indonesia), and as the command and control ship (the intention being that there will be at least one DDH for each of the MSDF’s four escort flotillas). As Kyle Mizokami points out in an article for the United States Naval Institute, “the Izumo has a 35-bed hospital, complete with a surgical suite and has accommodations for up to 450 passengers” in addition to the 500 sailors on board.
To be sure, I am not saying the Izumo will never carry fixed-wing fighter aircraft, but simply that it seems clear that this capability was not the motivating factor for acquiring the Hyuga, Ise, and Izumo, even if some strategic flexibility is built in. Even if the Izumo and its prospective sister ship were to carry aircraft however, it will likely be for at-sea air defense in Japan’s southern maritime defense perimeter, and not for offensive purposes. That said, as Kyle Mizokami notes elsewhere, even this use may not be a particularly smart use of Japan’s expensive helicopter carriers and the F-35B, and other options may be available to address this vulnerability. In reality the biggest “offensive” threat the Izumo could represent is not as an aircraft carrier but as an LPH, with the ability to carry a number of attack helicopters such as the Apache, and possibly in the future, the Osprey, which would supplement Japan’s amphibious capabilities. It is notable however that the Izumo lacks a well deck -the issue of amphibious capabilities will be discussed more in the next instalment of this series.
Future: A real aircraft carrier?
Given the above, it would seem, given the more than adequate naval and defense capabilities of Japan’s neighbours, the Izumo is not “war potential” and poses little direct offensive threat on its own or in tandem with the SDF’s other capabilities. Given Japan’s significant maritime defense perimeter, the concept of a “defensive” carrier for enabling the projection of aerial power to Japan’s southern extremities is not beyond the constitutional imagination if China’s naval build-up continues. The above discussion however has been solely focused on “war potential” within the context of Japan’s independent military strength. Even if Japan on its own is unable to present an offensive threat to other nations in the region, the tricky question is whether various capabilities, such as these carriers, will be used in combat missions other than the (obviously prohibited) unilateral use of force by Japan. Such missions could include UN collective security missions like the Gulf War, Afghanistan, or Libya, or missions involving the exercise of collective self-defense, which is particularly problematic, and touched upon in the final instalment of this series.
Special thanks to James Simpson and Mike Yeo for feedback on this article.
 Having only committed to purchasing the F-35A.
 The F-35B is the most expensive of the three F-35 variants, and the program has been put under increased scrutiny lately due to cost issues.
 There is no steam catapult for assisted launching of for example the F-35C carrier variant.
Corey Wallace joined Japan Security Watch in 2011. He writes on Japan security-related topics, focusing on issues and stories that may not find their way into the English language media. He also hosts the blog Sigma1 where he writes on Japanese domestic politics and broader issues in international relations.
Prior to taking up a PhD Corey was a participant on the JET program (2004-2007) and on returning to New Zealand he worked at the Ministry of Research, Science and Technology from 2007-2010 as a policy adviser. Corey lectures two courses at the University of Auckland. One is on the international relations of the Asia-Pacific, which contains a significant focus on East Asia security issues. The other is a course on China's international relations.
His primary academic interests before his current Japan focus were science and technology politics/policy, issues of ethnic identity, and Chinese modern history and politics. He carries over his interest in issues of identity and history into his PhD where he is looking at generationally situated concepts of national identity and their impact on foreign policy ideas in Japan.
Corey Wallace has 51 post(s) on Japan Security Watch