What to make of the latest row between China and America over Taiwan?

IS IT a crisis or just (show) business as usual? With China and America, it can be hard to tell. Almost immediately after the United States said that it intended to sell more than $6 billion-worth of arms to Taiwan, the Chinese went into a spin. They summoned the American ambassador to denounce this interference in China’s “internal affairs” (Taiwan is part of the mainland, says the government in Beijing), threatened to cut off military ties with the United States and said they would impose sanctions on American firms involved in the Taiwan deal.

None of this looks good for the world’s most consequential relationship. From global warming to the sickly world economy to stopping nuclear proliferation in North Korea and Iran, co-operation between the established superpower and the rising one is vital to world stability. Why should either want to jeopardise this relationship? …