Starting Saturday Dec. 31, the Interchange Association, Japan -- Tokyo’s de facto embassy in Taiwan -- will have a new name: The Japan-Taiwan Exchange Association. The new moniker, which was announced in a notice posted today on the association’s website, received a quick rebuke from China's Foreign Ministry, which said it was “extremely dissatisfied” by the Japanese government's implicit nod to Taiwan's Taiwaneseness. Though the prospective name change is undoubtedly the result of months of closed-door discussions between the governments in Tokyo and Taipei, the timing of the announcement could scarcely be more portentous. Considering U.S. President-elect Donald Trump’s protocol-shattering shot across China's bow in taking a phone call Dec. 2 from Taiwanese President Tsai Ing-wen and the accelerated Chinese efforts to isolate Taiwan diplomatically and intimidate it militarily, Tokyo’s move reflects the heightened geopolitical competition in East Asia and at the same time will contribute to that contest. It also...