Taking a page from the past and one from the future, the Defense Department is devising ways to fight a new kind of threat that requires the strategic tricks of ancient warriors and the untested tools of network-centric warfare.

Unless DOD changes how it operates and learns to defend its cyber networks, many military experts say it will not be able to wage an effective battle in the cyberwar that is emerging as the 21st century's biggest challenge.

The Pentagon is at a crossroads, said Air Force Lt. Gen. Charles Croom, the new director of the Defense Information Systems Agency and commander of the Joint Task Force for Global Network Operations (JTF-GNO). "Networks are too important to the warfighter to not have them when the warfight begins," he said.

Croom said DOD approaches computer network defense by emphasizing convenience to users, but the department's future information assurance strategy should tilt toward adding security.

"The threat is great," Croom said. "It requires constant vigilance."

Other countries — for example, China — crime gangs and thrill-seeking hackers could steal information about U.S. military war plans and weapon systems to gain intelligence and embarrass the Pentagon. The threat has caused DOD to re-evaluate information assurance policies and acknowledge that such reviews will continue.

In the past year, DOD implemented new policies to strengthen computer network defense. In 2004, DOD created JTF-GNO to operate and defend networks that operate under Strategic Command (Stratcom).

The department also approved a new command structure that identifies four military officials who will report to Croom. The National Security Agency published a new technical architecture guiding DOD's acquisition and use of information assurance technology. DOD also issued directives on managing ports, protocols and services, and requiring periodic computer security training for all department employees.

DOD turned to procurement to support these policies and develop new kinds of defenses for cyberattacks. First, the department chose Retina from eEye Digital Security to scan computers for vulnerabilities. Then, DOD selected Hercules from Citadel to patch computers. Next, the department built a new multimillion-dollar command center to monitor global network operations and picked PestPatrol, antispyware from Computer Associates International. DOD will soon begin testing Pest Patrol before introducing it later in the year.