The steady drip of diplomatic scandals between the U.S. and Chinese governments keeps coming, this time with a report, delayed for months, that China arrested one of its own security officials for allegedly spying for the United States.

We can infer from the fact that Reuters' exclusive report cites only unnamed sources and ran without a byline that the information comes on deep-deep background: Neither side wanted this to come out at all. The news, in short, is that an unnamed "aide to a vice minister in China's security ministry was arrested and detained early this year on allegations that he had passed information to the United States for several years on China's overseas espionage activities." The aide had been recruited by the C.I.A. and made hundreds of thousands of dollars in a case that "could represent China's worst known breach of state intelligence in two decades." These kinds of reports often cite unnamed official sources, but sometimes you'll get a clue as to where they work (U.S. diplomatic sources, for example). This time all three sources are simply identifies as people with "direct knowledge of the matter" who "all spoke on condition of anonymity for fear of punishment if identified."

Had China or the United States made the arrest public when it happened, "sometime between January and March," it would have come right as the Bo Xilai case was gaining momentum as China's biggest political scandal in years. And it would have just preceded the Chen Guangcheng debacle, a diplomatic headache between the United States and China. As it is, this new spy scandal will get the limelight all to itself -- that is, if reporters can get anybody else to talk about it.