The balance of power in Asia is shifting rapidly, with important consequences for Japanese security and the U.S.-Japan alliance. China's defense budget has grown 650% in real terms since 1996 and Beijing has spent that money effectively. The People's Liberation Army has become a formidable military force capable of challenging U.S. power at an increasing distance from the Asian continent. Its conventionally armed cruise and ballistic missiles, combined with a large fleet of modern warplanes, surface warships and submarines, could inflict heavy losses on Japanese and U.S. forces during the opening stage of any conflict.
Given this development and statements by President Donald Trump during his election campaign, American allies rationally fear that the U.S. may not fulfill commitments to defend them. They are evaluating how their own defense capabilities might be strengthened, either as a hedge against abandonment by the U.S. or preferably, as an inducement for the U.S. military to remain. These calculations are underway, with different tentative answers, in Europe as well as in Canberra, Manila, Bangkok, Singapore and Tokyo.
Japan has adopted a variety of measures to strengthen its security. It has embraced its U.S. ally more closely by integrating its space-based signals and image intelligence programs, loosened restrictions on its defense forces and lifted its ban on arms exports. It also has moved to deepen strategic relations with Australia, India, the U.K., France and several Southeast Asian nations. In December, Japan passed a bill to increase defense spending for the fifth consecutive year.
These measures are important and have been welcomed in Washington. But there should be no illusion: the balance of military power will almost certainly continue to shift against Japan and the U.S. China's defense budget is already three times that of Japan. Last year's PLA budget increase of 7.6%, the lowest since 1996, was still more than four times that of Japan. Moreover, China's military power does not yet fully reflect the size of its defense budget. The PLA has only recently begun series production of destroyers, among other systems, and it is now producing both those vessels and modern fighter aircraft at three times the rate it was just a decade ago.
The adjustments Japan has made thus far are best seen then as a beginning, rather than an end, of the effort to improve its defense capabilities. Japan needs to appreciate that defense requires more than a "sympathy budget" to reduce U.S. cost burdens. Both Japan and the U.S. will have to pull their weight if they are to be true military partners. U.S. expectations about its allies have evolved, a fact evident well before Trump's election.
Reforming Self-Defense Forces
There are measures Japan could take which may be relatively inexpensive but would require bureaucratic reforms that may be painful to particular organizations. For example, establishing a standing joint command, unifying the country's Ground, Air and Maritime Self-Defense Forces would greatly enhance effectiveness.
The budget process should be revised to provide the Ministry of Defense with the ability to evaluate rigorously the cost effectiveness of different ways to achieve particular missions. The fixed budget shares for the three services, which have not changed in a decade or more, should be abolished. The budget for the Ground SDF is roughly 60% larger than that of both the Air SDF and the Maritime SDF despite the greater array of air and naval threats facing Japan today.
Japan also needs a clear strategy to guide procurement and force structure. Given both the magnitude of the threat and the fact that the bulk of U.S. forces will take time to arrive in a conflict area, a sensible strategic approach would be an active denial strategy that would prevent an adversary from scoring a decisive blow before help could arrive.
To execute such a strategy, Japan first would need to adopt a resilient and survivable force posture, one that would enable its forces to absorb an attack and continue fighting. In the face of highly accurate ballistic and cruise missile attacks, the dispersion and mobility of key military assets would be critical.
U.S. forces in the Pacific are also adjusting to improve resilience and seeking ways to operate dispersed forces. New investment in military infrastructure, especially the preparation of civilian ports, airports and telecommunications, would greatly enhance the ability of both Japanese and U.S. forces to conduct an effective mobile defense.
A denial strategy would require emphasis on capabilities that contribute most directly to air and missile defense, local sea-lane defense, and isolating and striking against forces that land on Japanese territory. Building the capability to retake islands against an adversary armed with long-range precision strike abilities would be inordinately expensive and may not be practical for Japan beyond a certain scale.
Japan may not be able to replace its entire air fleet with sufficient numbers of stealthy "fifth generation" fighter jets like the F-35. It should therefore look at keeping a mix of newer and older fighters. It will need to further upgrade its F-15 fleet. And it might consider buying additional improved "fourth-generation" aircraft, which would be useful in defense against cruise missiles as well as against an air attack, especially when paired with the F-35.
The Air SDF should also invest in additional aerial refueling tankers. Tankers have sometimes been depicted as supporting offensive air capabilities, but they are critical to maintaining defensive combat air patrols, greatly increasing the effectiveness of aircraft by keeping them in the air and fighting longer.
For anti-ship missions, Japan should invest in new extended-range cruise missiles. These can be placed on Japan's outer islands to complicate the task of any attacker. To protect the fleet and sea lanes, the Maritime SDF might consider additional smaller air defense ships while it continues to build and improve its large and highly capable Aegis-equipped destroyers. It should also invest in additional missile reloads for all of its air and missile defense systems.
Finally, to ensure that it can move its military assets to the locations required as initial losses occur, Japan will want to ensure that its tactical lift is adequate and has redundant capacity to allow for losses to its air and maritime transport resources.
While the SDF is pursuing many of the above options in one form or another, it has made a number of inadequate compromises that limit effectiveness. It modernized parts of its F-15 fleet, but did so with inadequate mechanical radar, as opposed to active electronically scanned array radar, to save cost. The conversation on future fighter acquisition beyond the 40 F-35s on order is only just beginning. The Air SDF has procured only four aerial refueling tankers. Due mostly to local political opposition, only a handful of civilian airports have been prepared for military use. The ranges of Japan's anti-ship missiles have been extended, but only marginally. And surface-to-air and anti-ballistic missile reloads remain woefully inadequate.
To address even basic defensive needs, the Japanese military will need an increase in budgetary spending, but it will also have to focus its efforts and spend its money efficiently. Fixed budget shares mean that the Ground SDF has sometimes pursued novelty items, such as the acquisition of expensive Osprey aircraft, while the Air SDF and Maritime SDF have had to cut corners.
Similarly, the domestic development of certain types of large-ticket military items locks the Ministry of Defense into large production runs that may not be optimal. The Air SDF is set to acquire 40 C-2 cargo aircraft, for which requirements were written before the current threat to Japan crystalized. These planes can transport heavy loads as far as Hawaii and may be useful for transporting peacekeeping soldiers overseas. But they are almost certainly not the most cost-effective lift option for the defense of Japan, at least not in the numbers currently imagined.
The military environment in Asia is unforgiving and becoming more so. Japan will need to increase its defense spending to buttress deterrence, but it will also want to address bureaucratic practices that limit strategic rationality and flexibility as it examines its strategic options.
Eric Heginbotham isprincipal research scientist at the Massachusetts Institute of Technology's Center for International Studies.Richard Samuels is director of the center and Ford International Professor of Political Science at MIT.