So far as I know there is no evidence of the US doing that. Most of the US effort in cyberspace is defensive. China is the one attacking people and systems with hackers -- and the leaks show that.
Apparently Assange is holding back on what he calls the 'thermo nuclear device'
LONDON/MELBOURNE: Internet whistleblower WikiLeaks is holding back secret material, which it regards as "thermo nuclear device" to be released if it needed to protect itself as Australia said it would provide consular services to the organisation's founder Julian Assange if arrested.
Warning that Assange's legal pursuit in Sweden had "political motivations", his lawyer Marx Stephens said that WikiLeaks still held secret material which would be released if it needed to protect itself.
"The material being held back is like a thermo nuclear device", Stephens told BBC and said Assange would fight attempts to take him to Sweden to face rape allegations.
http://economictimes.indiatimes.com...thermo-nuclear-device/articleshow/7053016.cms