A congratulatory phone call to the president-elect of the United States would have been regarded as normal: a routine courtesy call that leaders the world over make when someone assumes a high political office. But a Donald Trump phone conversation last week with Tsai Ing-wen and his description of her as the ‘President of Taiwan’ seem to have stirred the proverbial hornet’s nest. China, which baulks at any diplomatic contact between America and the island, lodged a formal complaint with the US. The diplomatic ripples are being felt all over the Asia-Pacific.