1) The Japanese have been "re-armed" for decades. The fiction that they haven't (and that has been accepted by the naive and the gullible, and those just not paying attention) is maintaned by the facade of them calling their forces "Self-Defense Forces."
2) The Japanese Maritime Self-Defense Force is arguably the second most powerful Navy in the World.
3)In a naval war the likelyhood that the Japanese would not only defeat China, but humiliate them (and completely without US assistance), is quite high.
I have to admit I am out of date with Japan’s military. All I really remember was the grumbling of Japanese Neocons grumbling over Article 9.
China’s naval buildup seems to be directed towards this exact scenario. Do they have numerical superiority yet?
True, Japan’s Self Defense program is more than most people realize. But this is not your grandfather’s Japan. And I think their navy fleet is minimal in comparison to China (but I haven’t actually seen the comparison), not to mention the size of the armies. Plus, don’t forget that Japan has no nuclear weapons. Any military confrontation with China will require US involvement. And don’t think for a second that China doesn’t know it. This ongoing argument over those islands is just a way for China to see how much it can push the current WH until it pushes back, i.e. seeing if there really are no ‘red lines’ for Obamao.
And they have nukes.
Of course, the Chicoms may have more, but nukes have deterrent capabilities.