For China, Edward Snowden's sudden arrival in Hong Kong and his explosive revelations about the extent of US cyber-spying activities around the world are both a boon and a burden, a potential propaganda and intelligence gift, but also a diplomatic dilemma. Beijing has in recent months come in for sustained criticism over its own cyber-spying activities. The US government and private US internet security firms have criticised China for state-sponsored cyber-attacks, targeting everything from US military contractors to corporations in America. Evidence has been produced that purports to show Chinese hackers operating from military facilities targeting US media firms and private companies. US President Barack Obama was sitting down to tell Chinese leader Xi Jinping that US patience had run out and China had to rein in its cyber-spies, just as Edward Snowden's claims that America 's National Security Agency had been collecting vast amounts of information about internet users around the world were gaining attention. What's more, Mr Snowden now says the US was hacking hundreds of targets in Hong Kong and China, including private individuals, academics and students too. China has long said it is a victim of hacking. Here was a contractor for American intelligence who had fled to Hong Kong saying he wanted to expose US "hypocrisy"; China's claims, he said, were true.