Control, halt, delete

This week, an open letter appeared on Chinese blogs and online bulletin boards. “Hello, internet censorship institutions of the Chinese government,” it said. “We are the anonymous netizens. We hereby decide that from July 1 2009, we will start a full-scale global attack on all censorship systems you control.”

Beijing’s attempts to manipulate the internet would, the message predicted, “soon be swept on to the rubbish pile of history”.

Chinese internet users, although skilled at dodging the censors, are angrier than they have ever been. The anonymous declaration of war is just one sign of the strains emerging as the global spread of internet access, and its embrace by activists of all stripes, triggers an unprecedented crackdown by national governments that threatens to transform the way hundreds of millions of people communicate.