The United States military currently views cyberspace as the "fifth domain" of warfare - alongside land, sea, air, and space - and the Department of Defense, National Security Agency, and CIA all field teams of hackers who can - and do - launch computer virus strikes against enemy targets. In fact, as @War shows, US hackers were crucial to our victory in Iraq.
"The short history of the US and Cyber War"
Our surveillance state was born in the brain of Admiral John Poindexter in 1983. Poindexter, President Ronald Reagan's national security adviser, realized that the United States might have prevented the terrorist massacre of 241 Marines in Beirut if only intelligence agencies had been able to analyze in real time data they had on the attackers. Poindexter poured government know-how and funds into his dream---a system that would sift reams of data for signs of terrorist activity.
"Important context for privacy debate"