“What we’re seeing now is the end of a decade-long drive toward complete visibility into all computer networks of interest,” said Steven Chabinsky, a former senior FBI cyber-official who now works for the security company CrowdStrike.

China’s cyber-espionage assists the government’s broader efforts to quell internal dissent by identifying activists and dissidents and tracking them through their e-mail. China has been accused of hacking the servers of Google to obtain dissidents’ e-mail and of targeting nonprofit groups and think tanks that study China.

Some analysts say that more transparency is needed to address the issue. Google in January 2010 became the first company to disclose voluntarily it had been hacked through an intrusion originating in China. It also disclosed that its investigations had turned up dozens of other companies that had similarly been penetrated by China in hopes that some of them would also disclose the hacking. None did, though Intel later disclosed in a regulatory filing it had been targeted.