When the Democratic Party of Japan took power three years ago, it promised a radical overhaul of foreign policy.

It wanted to rebalance relations with the US and China, by addressing its “over-dependence” on the former and its strained relations with the latter. In a world moving from US unipolarity to multipolarity, in the words of Yukio Hatoyama, then prime minister, Japan would rediscover Asia as its “basic sphere of being”.

It was a grand vision. Today it lies in shreds. That became clearer this week with Tokyo’s replacement of its ambassador to Beijing after a flare-up in Sino-Japanese tension. Anti-Japanese protests erupted across Chinese cities at the weekend after a renewed war of words over the Japanese-administered Senkaku islands, called Diaoyu by China.