China’s increasing assertiveness in the East China Sea and a growing threat from North Korea’s missile development programme are pushing Japan to ramp up its own military capabilities, independently of the United States.

Last week, Japan announced plans to accelerate the deployment of the US-made anti-missile Terminal High Altitude Area Defense (THAAD) following the landing of a North Korean Rodong intermediate-range ballistic missile 250km off its coast on August 3.

That was followed by reports that Japan would also deploy a new missile system near Okinawa in response to frequent Chinese incursions into waters around the disputed Diaoyu islands – known in Japan as the Senkakus.

Japan is host to 84 US military installations, second only to Germany in number, including a THAAD facility near the ancient capital of Kyoto. But despite being under the umbrella of the US-Japan Security Alliance, the rising danger emanating from North Korea has convinced the government and defence ministry in Tokyo that the country needs its own capability to shoot down missiles, and needs it soon.

Before the THAAD announcement, South Korea had said Japan could share information gathered from the THAAD system it is jointly installing with the US. That was a reversal of previous pronouncements from Seoul and signalled growing cooperation with Tokyo. But since relations between the two US allies have been volatile in recent years, some feared an agreement could be short-lived. China’s growing military might appears for now to be pulling them closer together.

US must ditch deployment of THAAD missile-defence system

“Once South Korea and Japan have set up the sharing system, it would be difficult to stop,” said Jun Okumura, visiting scholar at the Meiji Institute for Global Affairs and a 30-year veteran of the Japanese civil service. “The South Korean and Japanese militaries have much better relations than the politicians and governments.”

Japanese and international media have reported that Japan has decided to put land-to-sea missile systems on the islands around Okinawa. But according to Hideaki Kaneda, a retired Japan Maritime Self-Defence Force vice-admiral, the issue is still under discussion.

“The other choice is to increase the number of ships with Aegis missiles or deploy Aegis on land, as is being done in Europe,” said Kaneda, currently a fellow at the Japanese Institute of International Affairs.

In September, China reacted angrily to Japan reinterpreting the pacifist Clause 9 of its constitution to allow its military a more active role. And since Prime Minister Shinzo Abe won a ‘super majority’ in July elections, he has been in a position to attempt full revision of the US-imposed post-war charter.

China is likely to see any strengthening of the Japanese military as a justification to boost its own considerable defence spending.

South Korean President Park Geun-hye defends THAAD and urges Pyongyang to abandon nuclear programme

While some in Japan worry about American willingness to back its biggest Asian ally in the region should disputes with China escalate, others still see the signals from Washington as supportive nudging of Japan to develop its own defence capabilities.

“The US has always encouraged us to take more responsibility for our own defence. Whether you see that as support, as the Abe administration does, or pressure depends on your perspective,” says Okumura.

Grant Newsham, a senior research fellow at the Japan Forum for Strategic Studies and a retired US Marine colonel who acted as a liaison with the Japanese Self-Defence Force (JSDF), doesn’t see the US pushing Japan to develop an ‘independent’ military.

“The US encouragement of the Japanese to improve their defence capabilities has always been done with the idea of a more capable and useful JSDF, operating together with US forces. Wanting the JSDF to be more capable does not translate into wanting the JSDF and Japan to operate independently,” says Newsham.

“Indeed, it’s surprising how little the Americans have required the Japanese to do in exchange for the services of the world’s most powerful military.”

Meanwhile, Japan’s THAAD deployment is “receiving attention from China, as did the announcement of deployment in South Korea, because it does change the strategic balance in favour of Japan,” said Okumura.

The US wants its THAAD missile system in Asia because of this mobile North Korean weapon

Okumura believes the Chinese military will take THAAD as an opportunity to leverage domestically for more resources, but despite the growing tensions, he sees little chance of a full-blown East Asian arms race.

“China has been increasing its defence budget by more than 10 per cent annually for three decades. There’s already a race going on, between a hare on steroids and a tortoise that never sleeps. When Japan increased its defence budget by 2 per cent, it was seen as a big deal, so it will be extremely difficult for it to increase it significantly,” said Okumura.

But according to Newsham, “China will consider anything and everything Japan does defence-wise as a provocation.”

Newsham notes that, “for at least the last five or six years there have been quiet concerns in parts of the Japanese establishment over whether the Americans really will back Japan in a fight with China over the Senkaku Island or suchlike,” but sees those fears as unfounded. “An adversary would be ill-advised to think the United States will not, at the end of day, support a friend such as Japan, and support it with overwhelming force.”