From the moment they appeared, Edward Snowden’s revelations have been making life awkward for Barack Obama. Before his first summit with Xi Jinping, his Chinese counterpart, the US president stressed he would be raising as a priority the issue of Beijing’s frenetic cyber espionage activities. The day before the meeting, however, the UK’s Guardian newspaper published the first slew of allegations leaked by the former contractor for the US National Security Agency, revealing the breathtaking extent of America’s espionage programme.