information warfare
n. A form of warfare that attempts to disrupt or disable an enemy's computers, networks, and other sources of information.
Small campaigns of information warfare are becoming quite commonplace. The Pentagon's computers appear to be under almost continual, though largely unsuccessful, bombardment from hackers who see it as a special challenge. All this has led to anxieties that new opportunities are opening up for hostile states or terrorists. According to the National Defense Panel of the United States, "information warfare threats to the United States may present the greatest challenge in preparing for the security environment of 2010-2020."
—Lawrence Freedman, “Computers, viruses and war,” Newsweek, April 27, 1998
Military scholars call it information warfare, and increasingly the literature of military theory is replete with references to data weapons, logic bombs, net war, virus insertion, battlespace, cyberterror and hacker warriors.

This is not the nerdy slang of 14-year-old cyberpunks nattering about the latest version of Mech Warrior 2 or Total Mayhem 3-D or any of the other computer games designed to permit underweight hormonal teenagers to blow things up and rip virtual people apart with impunity.

This is the emerging, still-unformed jargon of serious scholars who write very dry papers for the U.S. School of Information Warfare and Strategy at National Defence University in Washington, D.C. Or for the Air Force Information Warfare Centre. Or for the Rand Corp., a strategic think-tank that consults to government.
—Stephen Hume, “War in cyberspace,” The Gazette (Montreal, Quebec), February 28, 1998
1981 (earliest)
Moreover, the value of leaked information is generally discounted on the assumption that material is being divulged selectively to make the sponsor of the leak look good. A form of information warfare develops, with an escalation in the numbe leaks, and with foreign intelligence establishments learning a great deal about America's military capabilities.
—Paul Bracken & Martin Shubik, “Leaking strength,” The New York Times, February 05, 1981