An increasing number of attacks carried out over the internet have explicitly political goals, according to a report by security firm McAfee.
The US, Russia, France, Israel and China are armed with cyberweapons, the report said, with the UK, Germany and North Korea preparing for a future in which conflict is partly conducted through the internet.
Many nations are arming to defend themselves in a cyber war and readying forces to conduct their own attacks, the 2009 Virtual Criminology Report said.
The UK government recently announced plans to create a central Office of Cyber Security (OCS) to deal with the rising level of online attacks.
"The OCS will have a role in coordinating offensive capabilities and, in extreme cases, would have the ability to mount a cyber attack in response to intrusions on UK networks," the report said.
A cyberattack against government networks and critical infrastructures can result in physical damage and death, the report said.
"Today the weapons are not nuclear, but virtual, and everyone must adapt to these threats," said Dave DeWalt, chief executive at McAfee.
In most developed countries, critical infrastructure is connected to the internet and lacks proper security functions, leaving these installations vulnerable, the report said.
Critical infrastructure is privately owned in many countries, which the report said makes it a huge target for cyberwarfare.
The report, based on contributions by more than 20 international relations experts, calls for a public discussion on cyberwarfare.
Without insight into the government's cyberdefence strategy, the private sector is not able to be proactive and take proper precaution, the report said.
Cyber attacks will increasingly become a component of war in the next 20 to 30 years, according to report contributor William Crowell, a former deputy director of the US National Security Agency.
"What I can't foresee is whether networks will be so pervasive and unprotected that cyber war will stand alone," he said.