Japan seems willing to put themselves in harm's way here. From what i understand, they will engage in this defence of tian. The reason that japan is concerned is obviously because japan and china are historic adversaries. They do not like each other. And they don't want to see china nibble away at their sovereign territory. Japan gets 90 % of its energy through the tiwan strait. So for them, and you know, the last time that a country cut off japan's power, ah, japan went to war.