Admiral Chris Barrie, chief of the Australian Defence Forces, told a weekend conference in Sydney that more than 30 countries had advanced and aggressive programmes for waging war by computer.
Highly computerised nations like the United States and Australia were particularly vulnerable and had to protect themselves, Admiral Barrie warned.
Addressing a conference on Asia-Pacific security at Sydney University, the admiral said computer warfare programmes were a cheap and effective way to attack.
Stability challenged
"Cyberattacks will provide both state and non-state adversaries with new options beyond mere words but short of physical attack," he said.
He predicted that such programmes would become a full part of a country's arsenal over the next decade and beyond.
Admiral Barrie also warned that the Asia-Pacific region had embarked on a major weapons modernisation spree, posing a serious challenge to stability.
"The introduction into the region of high technology warfare capability, the development of weapons of mass destruction...and the increased threat from non-traditional military sources are serious challenges for the region and we need to address them."
Failure to do so, he said, would have far-reaching ramifications for the region's stability.
Arms market
Admiral Barrie noted that Pakistan and India had not only gone nuclear but had also developed long-range ballistic missiles that could reach targets outside South Asia.
North Korea, meanwhile, continued to export missile technology.
His view was shared by Pentagon official Peter Verga, US deputy under-secretary of defence for policy support.
Mr Verga said the Asia-Pacific region had been identified in the mid-1990s as the next great growth area by arms manufacturers.
That was briefly halted by the 1997-1998 Asian economic crisis, but as economies recovered, the potential for arms sales returned, he said.