Re: How did they find out it was China?
Just a process of elimination, we have some embarrassing news coming, so what can we give to the press that would distract the public - need to have something that was dangerous but thwarted - but don't want to suggest its a country that we've painted as inferior to the choices were Russia or China - now, as Russia has already been accused of cybercrime, to accuse again would imply we are somewhat incompetent at combating them so China is the obvious choice.
Far more fun looking for the news that this announcement is designed to distract from
Biting the hand that feeds IT
