It is certainly not an exercise in futility for Japan to defend their claims to the Senkaku Islands:
While much is made of Chinese efforts to upgrade their navy and air force, these two services are still inferior to the Japanese navy and air force. The Japanese have more modern and effective ships and their crews are far more proficient than their Chinese counterparts. Same thing with the Japanese Air Force. Moreover, the Japanese naval forces are themselves overshadowed by American warships assigned to the Western Pacific. In addition to the Japanese and American forces the Chinese have to worry about the formidable Taiwanese air and naval forces as well those of South Korea. Technically Russia is an ally, but the Russians keep most of their air and naval forces out of the Pacific and are inclined to continue their tradition of never having been at war with the United States. So China has to be careful. Any confrontations with Japan at sea in the air have to be handled carefully because China is still playing with a weak hand.
I judge that Japan has the edge in an aero-naval fight. But such a fight would be dangerous if it goes on. China has nukes and Japan's ally (that's us) has nukes. When nuclear-armed powers square off, the pucker factor goes up enormously, no?
Further, I think Japan is making a mistake by assuming that Japan can reach the islands first in a crisis.
Because I don't think the balance of power will necessarily stay China's hand--especially if the Chinese think they can slip into the Senkakus quickly and set up shop, daring Japan to do something about it. This is how China has conducted a creeping annexation in the South China Sea region.
And even if the Chinese expect a fight, China might decide to take the islands. Chinese leaders could easily believe they are more powerful than a cool analysis would show.
UPDATE: Oh, and we're updating our defense cooperation agreements with Japan. Japan is shifting their defense focus from Russia to China (with North Korea a dangerous factor to be coped with).
