The Pentagon has once again pointed accusing fingers at China, this time for what it claims was an "unsafe" intercept of one of its spy planes by two Chinese fighters over the South China Sea on Tuesday. But as a Chinese proverb observes, the offender complains first.

The US has again defended its innocence by stressing the spy plane was flying in international airspace. But this was contradicted by the Chinese Ministry of National Defense, which said it was "extremely close surveillance of China by US military aircraft."

Because the two militaries have agreed upon a code of conduct to control risks and to deal with unplanned encounters at sea and in the air, the event will probably end up as just another footnote in the history of the perennial cat-and-mouse game on China's doorstep.