Now another factor looms for China from a study (via Real Clear Politics) of the region:
Specifically, it says, "if a military confrontation occurred between the United States and China over Taiwan, U.S. policymakers can rest assured of Japan's support."
China's decision-makers must balance a little more complexity. This should increase uncertainty and therefore encourage deterrence.
But if the Chinese think they can win anyway or don't believe Japan will intervene, a bigger net of outside interests may also guarantee that no conflict over Taiwan will remain an "internal" matter for Peking to decide.
But it is good that Japan cooperates more over Taiwan.
And as an aside, have we actually alienated any ally over Iraq other than Germany? You know, not counting the pre-alienated French and Belgians?