If there's anybody to blame for a militarily aggressive Japan, it is nobody else but China. For the last 70 years, Japan had remained focused on protecting itself. When China unilaterally claimed the entire South China Sea, the equation in the contested shoal and reef drastically changed. Not only is Japan changing its pacifist constitution to allow its troops to come to the aid of its neighboring allies. There's also an arms race going on, as China ignores all pleas to stop its considerable reclamation of the ocean seabed, turning submerged reefs into islands where they built runways and garrison on them.

Mercene, F. (2015, September 25). South China Sea arms race (1). Manila Bulletin, p. 11.