About a year ago, I was in the office of Albert del Rosario, the foreign minister of the Philippines. What, I asked, would Manila say if Shinzo Abe, then running for prime minister of Japan, carried out his pledge to amend the pacifist constitution and “rearm”? (In fact, Japan is already fully armed, but its constitution bars use of force except in self-defence.) I fully expected him to reply that this would be a regrettable move. Not only would it be enormously provocative to China but memories of the country’s invasion of the Philippines, in which rape and civilian slaughter were common, were surely just as raw in Manila as they were in Beijing and Seoul. Not a bit of it, he said. “We would welcome that very much. We are looking for balancing factors in the region and Japan could be a significant balancing factor.”

Those remarks, echoed by Indonesia’s foreign minister, came back to me this week as China and Japan squared off dangerously over disputed islands in the East China Sea. At the weekend, Beijing took many by surprise when it announced the creation of an “air defence identification zone” covering the islands known as Senkaku by Japan and Diaoyu by China. There is nothing unusual about establishing such a zone. Many countries have them, including Japan and the US. Yet the move is provocative because China’s zone overlaps Japan’s. From now on, Beijing says, aircraft entering the zone will have to identify themselves to Chinese authorities or face unspecified “emergency defence measures”.

Mr Abe denounced the move, which he said had no legitimacy. Washington, too, has strongly objected. It sent two B52 bombers across the zone – without telling Beijing in advance – to underline its displeasure. Japan’s two main civilian airlines initially complied with the order but, under pressure from Tokyo, resumed flying across the zone on Wednesday without informing Chinese authorities.