ON SEPT 11, the Japanese government made the decision to acquire ownership of three of the five major islands constituting the Senkaku Islands - Uotsuri-jima, Kita-kojima and Minami-kojima - at the price of US$26 million (S$32 million). Of the other two, Taisho-jima has been owned by the government since the Meiji period and Kuba-jima is still owned by a private Japanese citizen.

In my view, the Japanese claim that the islands belong to Japan is rock solid.

The Japanese government formally incorporated the Senkaku Islands in 1895. From 1956 through 1978, American forces actively used two of the islands - Taisho-jima and Kuba-jima - as gunnery ranges named Sekibi Sho Range and Kobi Sho Range respectively, and the United States still maintains the right under the US-Japan agreement of 1972 to use them for military purposes.

The Chinese government never protested against the use of these ranges by the US forces. It began claiming the islands - which it calls Diaoyu - only in 1971, three years after a survey conducted with the support of the then UN Economic Commission for Asia and the Far East suggested possible oil reserves in the East China Sea.

Given the solid nature of the Japanese claim, it was puzzling to see the Japanese government take the step to create tension first by acquiring the islands, highlighting the existence of the dispute which the government has refused to acknowledge.

There are two explanations for this.

• First, nationalist Tokyo Governor Shintaro Ishihara's decision to purchase the islands almost forced the Japanese government to purchase the islands pre-emptively.

In April this year, Mr Ishihara announced that he would buy the islands and construct facilities such as a small harbour for fishing boats and a radio communication station in order to consolidate Japan's effective control over the islands.

However, his action contradicted the Japanese government's position that there was no territorial dispute and its expectation that construction of such facilities would invite a strong reaction from China.

China had dug itself into the position where renouncing its claim on the islands would undermine the political legitimacy of the Chinese Communist Party.

As a result, the Japanese government was given two bad options: Leave the fate of Sino-Japanese relations to Mr Ishihara or buy the islands. It chose the latter option.

• Second, Japanese citizens are growing more concerned about the fate of the Senkaku Islands, and a good number of them see it as imperative for Japan to "get tough with China" even at the risk of confrontation.

They think China is getting more assertive, challenging the rights and position that Japan has enjoyed in the last 100 years.

In 1992, China enacted a law concerning its territorial sea, designating the Senkaku Islands to be Chinese. In 2010, China overtook Japan to become the world's second largest economy.

In the past decade, Chinese military expenditure has grown by a staggering 170 per cent, while that of Japan has declined by 2.5 per cent. Just over a week ago, China's first aircraft carrier became operational.

As a result, Japanese citizens have come to suffer from a siege mentality. This is shown in a public opinion poll conducted jointly by Japanese independent think-tank Genron NPO and the China Daily this year prior to the Senkaku debacle.

The largest number of Japanese respondents (excluding "don't know" answer) thought that Japan would become a "middle power with no influence" by 2050. In contrast, the largest number of Chinese respondents said Japan would become a "great militarist power", followed by the answer that it would become a "middle power with strong influence".

In other words, Chinese citizens actually regard Japan's power more highly than their Japanese counterparts.

Also, while 31.8 per cent of Chinese respondents had either a "good" or "relatively good" impression about Japan, only 15.6 per cent of Japanese respondents had the same impression about China.

And while 64.5 per cent of Chinese respondents had either "bad" or "relatively bad" feelings towards Japan, an overwhelming 84.3 per cent of Japanese respondents felt this way towards China. Despite the flare-up of anti-Japanese sentiment in China, Chinese citizens in general are more relaxed in their attitude towards Japan than Japanese citizens are towards China.

In declining Japan, "getting tough with China" is regarded as an imperative to overcome its deteriorating power position. In rising China, "getting tough with Japan" is considered to have become a feasible and necessary option for China to recover its great power status.

Japan cannot simply get tough and get away with it, however.

Its actions, no matter how legal and legitimate, will have consequences. China is its largest trading partner, with bilateral trade hitting US$345 billion last year, and more than 20,000 Japanese enterprises now operate in China.

The same applies to China. Japan is the largest investor in China with investments of more than US$6 billion last year.

If Japanese companies decide to leave China and/or stop investing in China, that would further exacerbate China's economic downturn.

In addition, unless Chinese leaders and people understand not only the interests of China's neighbours but also their psychology, it would be difficult for China to achieve a "peaceful rise".

China's attempt to rise would be resisted if it continues to ignore international norms and rules, and allows its people to physically harm foreigners and vandalise their properties only because they disagree with them.

There is another issue at hand. If the origin of this territorial dispute was a need for natural resources, we should focus on addressing that very issue.

Fortunately, there has been important progress in developing and exploiting different energy sources in recent years.

The shale gas revolution has given the US a 100-year supply of natural gas. Russia and Japan are developing oil and natural gas fields in Sakhalin. China has made a big investment in renewables.

Japan may have suffered a nuclear disaster last year, but it will be able to construct the world's safest nuclear power plants if it can learn from it. In the high-tech environment of today, what makes the difference in energy development is availability of capital and technology more than abundance in reserves.

In this context, the Sino-Japanese agreement in June 2008 is of critical importance.

The two sides agreed to set aside the issue of how to delineate the median line in the East China Sea and decided to undertake joint development of oil and gas fields in the area. Bilateral talks have been stalled since 2010, but now is the time to go back to the negotiating table.

In a world with growing energy demand, we do not have the luxury of fighting for energy. We need to cooperate for it.

The writer is associate professor at the National Graduate Institute for Policy Studies (Grips) in Tokyo, where he is director of the Security and International Studies Programme. He is the author of North Korea's Military-Diplomatic Campaigns, 1966-2008.

By Invitation features leading writers and thinkers from the region and Singapore.