All nations protect their economic interests. Defense includes protecting logistical and natural resource supply lines. There is a cross-over point where national economic interests offensively use the military for securing natural resources or territory. Claim of right accompany or precede these interventions.
China’s recent action in the South China Sea is illustrative of this transition. China, like other countries in the region, have a population issue, the support of which necesitates increased resources, as well as efficiencies. The interest in these islands by all claiming countries have more to do with natural resource potential and accompanying territorial water boundaries, than with national pride. To date only 12 nautical mile territorial waters have been asserted through Hainan Province, which administers South China Sea claims. Territorial waters effect sea trade and shipping (especially, naval) pass through rights, as well as economic and national security control issues. A 200 nautical mile EEZ assertion would ultimately create too much conflict in the area.
The question is one of taking vs. paying. China could enter into business arrangements with any of the other states that claim these islands and the associated natural resources. In fact, to the extent that it would affect deep sea mining in international waters (i.e., not within territorial waters) there is already a U.N. developed independent agency established, with arbitral procedures in place, at least to address exploration at this juncture. It is still a particularly weak organization from an enforcement standpoint, so this would not inhibit countries that otherwise might want to “take”. It would not address the gas and oil interests, but China has negotiated with other countries for these resources throughout the world. It is better to pay nothing, than something, but the cost of military involvement and destablization of reputation and trading relationships is something. The question is why are these particular economic interests different and who would be benefiting in China?
The U.S., England and other historical world powers have all gone through (and still go through) periods where economic interests extend their reach over the military, beyond defense necessities. In the long run, it is a short-sided position.