The single largest factor in confused territorial claims and counter-claims in the South China Sea is China’s hotly disputed insistence that it has sovereignty over nearly all of the sea as defined by its acquisitive Nine Dash Line. One-third of all global shipping passes through the sea, and there are large untapped oil and mineral reserves below the water. All of the South China Sea’s littoral states have some competing claims, but none are so wide-ranging or dangerously damaging to international stability as China’s.

China first built a shaky-looking structure on Mischief Reef in 1995 but what has caused great alarm this week is that the US Navy has just revealed that China is currently engaged in building large sandbanks on shallow submerged coral reefs in the Spratly and Paracel Islands, reinforcing them with concrete quays, and then constructing buildings and harbours. These “forward naval stations” mean China is strengthening its military presence in these sensitive islands where it disputes the status quo shared by Taiwan, the Philippines, Brunei, Malaysia, Indonesia and Vietnam.

Rather than heading for a dangerous military clash with incalculable effects on vital international shipping routes, the better way forward would be to work with the 2002 China-Asean Declaration of Conduct, in which all the parties committed to “exercise self-restraint in the conduct of activities that would complicate or escalate disputes and affect peace and stability”. This does not include building fortified sandbanks. And it does not include letting China’s Foreign Minister Wang Yi get away with claiming that China’s construction work is “legal and reasonable”.