UNTIL this month relations between Vietnam and China seemed only to be improving. Business deals were being done and trade was humming. The Communist neighbours were discussing the possibility that they might jointly prospect for oil in the South China Sea, where they have long disagreed over conflicting territorial claims.
But the calculus changed abruptly when China National Offshore Oil Corporation towed a $1 billion oil rig into waters just 120 nautical miles (220 kilometres) off central Vietnam’s coast. China announced that the hulking structure would stay put until the middle of August. To make that perfectly clear, it sent a flotilla of ships, which Vietnam says included armed vessels. This is all taking place not far from the Paracel islands, which China seized from the American-backed South Vietnamese regime in 1974.