Twenty years ago, at the peak of the Cold War, the US Air Force looked into the possibility of severing the Kremlin's communications links and cutting Moscow off from its air defense elements. The idea was before its time, though, and nothing came of it.

By 1990, considerably more was possible. Air Staff planners in the Persian Gulf War identified 78 command-and-control nodes whose elimination would paralyze Iraq. These nodes were among the first targets struck. Twenty-eight minutes after the war began, Iraqi units were shut off from higher echelons, with no intelligence or direction.

The command-and-control attack in the Gulf was carried out with missiles and bombs. In the future, such operations may instead use information itself as a weapon and strike by means of computer viruses, logic bombs, deceptive jamming, swamping the adversary with data, or the alteration of information the enemy believes to be true.

Information warfare continues to evolve and grow in importance. Nobody knows what will happen next, but for millions of Americans, the experience could move closer to home. Hacker sites on the Internet offer both targeting data and the tools to conduct an attack. The microchip revolution has made an incredible amount of information available.

For about $1,500, you can buy a CD-ROM, "Local Exchange Routing Guide," which gives the address of every major telecommunications switch in the US and enough information to estimate the capability of each of them. Doubtless, it is a great resource for those with a legitimate need for the knowledge, but it could be an equally great resource for others, such as terrorist organizations, whose needs are not legitimate.

A Presidential Commission exploring the vulnerability of critical national infrastructures that range from the banking system to the water supply and continuity of government finds that 70 percent of what binds these infrastructures together is telecommunications connectivity. Thus, targeting intelligence about our central vulnerability is for sale on a computer disk.

So far, the incidents that have made news have been about hackers and small-scale assaults on computer systems, but some 18 nations have active information warfare programs. When nations go to war in the future, information will be at the crux of it. "Joint Vision 2010," published last summer by the Joint Chiefs of Staff, says that information superiority will be the pivotal factor in establishing "full spectrum dominance" of a battle area.

A prominent role in this must go to the Air Force, which presently fields the heavyweights of the information war with the E-3 Airborne Warning and Control System, the U-2, the E-8 Joint STARS, and the RC-135 Rivet Joint. These aircraft are among those most in demand around the world today. The Air Force's role will almost surely increase as it moves toward greater emphasis on space and unprecedented global awareness, made possible by sensors in the electronic, visual, radar, and infrared regimes.

The Air Force has identified information superiority--the power to gain, exploit, defend, and attack information--as one of its six core competencies. The Air Intelligence Agency opened the Information Warfare Battle Lab at Kelly AFB, Tex., on March 17. An Information Warfare Center and an information warfare squadron were already in existence.

The Air Force's top information warfare priority is to defend its own information-intensive capabilities. Beyond a certain point, however, the independent protection of information capabilities is not possible. More than 90 percent of military communications are carried by commercial channels, for example. For most of their information technology needs, the armed forces must look to the commercial world, which is well ahead in the development of networks, imaging, storage and retrieval, and processing of information.

Ultimately, the emergence of information warfare will upset traditional concepts about conflict and national defense. The borderlines between military, police, and civil responsibilities will blur even more than they have already. We may have to redefine what we mean by an "act of war" and reconsider what constitutes an appropriate response. It will not be long until most nations and various other interests will have regular access to information, reconnaissance, and surveillance systems in space. Sooner or later, we will face questions that were previously unthinkable, such as under what circumstances the United States might shoot down somebody's satellite.

Other kinds of conceptual adjustments are also indicated. The Clean Air Act of 1990 required major petrochemical facilities--of which there are about 56,000--to identify and report "worst case" scenarios of what could go wrong in the event of various kinds of disasters. The law requires that this information be made available to the public.

Telling local citizens about a plant down the road is obviously a good idea. Releasing the data in aggregate, which the federal government has been remarkably slow in ruling out, is another matter. Disclosing the most effective way to attack computer-dependent petrochemical plants from coast to coast would be an enormous strategic blunder.

We have not yet figured out how to balance the benefits of an information superhighway with the danger of it being used against us. Getting that straight has to be a priority for the nation as the potential consequences of the information revolution unfold.