NORFOLK, Va. (AP) _ The U.S. military conducted a form of computer warfare against Yugoslavia as part of NATO's air war last spring, the military's top officer acknowledged for the first time.

Army Gen. Henry H. Shelton, chairman of the Joint Chiefs of Staff, made the remark during an interview Thursday in which he discussed the Pentagon's decision to assign U.S. Space Command the responsibility of coordinating both the defense of military computer networks and attacks on enemy networks.

Asked broadly if U.S. information ``weapons'' were used against Yugoslavia during the Kosovo campaign, Shelton replied, ``You can assume that we in fact employed some of our systems, yes.'' He said the ``systems'' were offensive in nature, but he would not be more specific about how they were used.

A defense official said later that Shelton was referring to a broad range of ``information operations'' involving computers that may have included cyber-attacks on Yugoslavia's air defense network. Shelton would not specify the target of the U.S. computer attacks and did not discuss the results.

``I would rather not be specific about how we used it, to be frank,'' he said. ``I don't want to divulge too much.''

The Pentagon has been pursuing research on offensive uses of computer viruses and other means of cyber-warfare for at least several years. Shelton said Space Command would coordinate the development of such techniques, starting next year, in addition to working on U.S. defenses against such attacks.

Shelton spoke to reporters traveling with him and Defense Secretary William Cohen aboard an Air Force jet from Norfolk, where they attended a ceremony to mark the renaming of U.S. Atlantic Command to U.S. Joint Forces Command. The change is part of a broader revision of the Unified Command Plan that includes the assigning of computer network defensive and attacks responsibilities to Space Command.

At a news conference after the ceremony, Shelton said the Pentagon is concerned about the vulnerability of military computers to intrusions not only by private hackers but also by enemies in times of war.

``I don't think there's any question, as we look to the future, that our information systems throughout America and specifically within the Defense Department will be more and more subject to attack,'' Shelton said.

Space Command, headquartered at Peterson Air Force Base in Colorado Springs, Colo., was given the responsibility to develop defenses against attacks on military computer networks as of Oct. 1. One year later, it will take on the added task of coordinating the development of offensive ``weapons'' for cyber-warfare, several defense officials said. The individual services are doing that work now.

Space Command's main mission is to provide missile warning and space surveillance as part of the air and space defense of the United States and Canada. It also plans for strategic ballistic missile defense.

At the Norfolk ceremony, Cohen said that the newly named Joint Forces Command, commanded by Navy Adm. Harold Gehman Jr., has been given the added responsibility of coordinating U.S. military support to civilian agencies in the event of an attack on American territory with nuclear, biological or chemical weapons.

Cohen stressed that the Joint Forces Command would be in a support role in such an event, leaving a civilian agency such as the Federal Emergency Management Agency or the Justice Department to take the lead. Even so, some civil liberties groups contend that involving the military is a mistake.

``We are supposed to believe that turning our military into a national police force will somehow strengthen our democracy?'' American Civil Liberties Union official Gregory T. Nojeim asked rhetorically.

Gehman said the military should be used to help respond to major disasters, as it does now in the case of hurricanes, floods and other natural disasters.

``I should think the taxpayers would be upset if they thought that we weren't preparing to help out the citizens in the case of a catastrophic event,'' Gehman said.