The Chinese cyber army keeps getting better, and that includes covering their tracks. It may take a defector or three to make it definite that China is waging a stealthy war over the Internet. Meanwhile, the Chinese reap enormous economic and political benefits from their raids on economic and technical secrets in the West.
This is not trivial and we need to wage offensive cyber-warfare and not just attempt to parry their attacks. The Chinese have no incentive to stop until we inflict pain on them with our own attacks.
The Chinese are learning just by attacking us, even aside from whatever they bring back home.
