At about 9.50pm on the evening of June 8, a Russian destroyer and its support vessels sailed north into the 24-nautical mile contiguous zone around the disputed island chain that Japan calls the Senkakus and China the Diaoyu. So began an international incident that touches half of the world, from Beijing to Moscow, Delhi to Washington.

Warships are free to navigate the contiguous zones of other nations and Russian ships had passed this way before. But at about 12.50am on the morning of the June 9 a Chinese frigate for the first time ever entered the contiguous zone sailing south. A tremor went up the Japanese chain of command until China’s ambassador to Tokyo was summoned from his bed.

At one point the Chinese vessel sailed directly towards an island, prompting fears in Tokyo of a landing. But then it curved round to intercept and match the Russian vessel’s course, with the ships departing to the north-east at 3.10am. Japan complained. China rejected the complaint, saying it has every right to sail in its own waters.