The Google hack, at a time when the company was facing increasing hostility in China, appeared to leave little room for doubt; one Chinese source actually told officials in America’s State Department that two members of the elite Politburo Standing Committee ordered the attack, according to a State Department cable that was released by WikiLeaks. Other victims of hacking attacks included the International Olympic Committee and the World Anti-Doping Agency after the 2008 Beijing Olympics; Tibetan and Uighur activists and Chinese dissidents; think-tanks that analyse China (including its hacking capabilities); and NGOs operating in China. None of these seemed to have any commercial value.

For an individual caught up in such an attack the effect can be creepy. One day in early 2010 an American working for an environmental NGO in China noticed something odd happening on his BlackBerry: it was sending an e-mail from his account without his doing. He watched, dumbfounded, as the e-mail went out to a long list of US government recipients, none of which was in his address book. Seconds later he saw the e-mail disappear from his sent folder. Eventually he heard from the FBI that his e-mail account and those of several colleagues had been compromised by hackers from China. All the victims had attended a climate-change conference in Copenhagen in December 2009 where America and China had clashed.

Another obvious target was David Barboza, a journalist on the New York Times. In October 2012 he reported that relatives of Wen Jiabao, then China’s prime minister, had amassed assets of $2.7 billion. After the story was published, said the newspaper, Chinese hackers compromised its networks to get at Mr Barboza’s work e-mail account. Following the newspaper’s disclosure in January, other news organisations, including the Wall Street Journal and Reuters, noticed similar Chinese intrusions. But Bloomberg, which last year reported on the finances of relatives of Xi Jinping, China’s new president, and has extensively investigated Chinese hacking, has denied suggestions that it was itself successfully hacked.