Nick Harvey has emphasised the cyber threat facing the UK, saying it is "a matter of time" before terrorists use it as a method of attack.
In a speech in London, the armed forces minister warned that, in the wrong hands, a laptop could be as effective a weapon as a cruise missile.
He also set out how the government planned to use cyberspace to help the military fight the wars of the future.
All parties see cyber warfare as one of the UK's biggest emerging threats.
In the government's recent national security strategy, cyber security, alongside terrorism and a flu pandemic, was identified as a "tier one" threat to the UK - meaning the government was giving highest priority to these issues.
It will spend £650m over the next four years on a National Cyber Security Programme, aimed at protecting individuals and the national infrastructure from hostile computer attacks.
However, Labour says the plans are a "reheated" version of its own approach while critics say government efforts are disjointed and officials are not taking advantage of external expertise.
Mr Harvey told Chatham House that the consequences of a cyber attack against the country's critical infrastructure could be "catastrophic".
"The fact that cyber security has been identified as one of the top national security threats for the UK over the next five years indicates both the likelihood of such an attack and the level of impact," he said.
"It can only be a matter of time before terrorists begin to use cyber space more systematically, not just as a tool for their own organisation, but as a method of attack," he said.
The public should not just focus on the threats posed by cyberspace as the government was still excited about the way the internet and digital technology enables people to expand their horizons and express their freedoms.
But he said governments across the world would have to establish laws governing cyberspace and how it is used, in accordance with existing legal frameworks.
BBC defence correspondent Jonathan Beale said Mr Harvey had spelt out his belief that the threat was real and the government must work with industry and academia to combat it.
So far the focus has been on the threats posed to the UK, he said, rather than how Britain could use cyber warfare to enhance its conventional military capabilities.
There have been warnings from ministers and security chiefs about the threat in recent weeks.
Last month, the head of GCHQ, Iain Lobben, said 1,000 malicious e-mails a month were being targeted at government computer networks.
In a rare public appearance, the intelligence agency's director said the UK's critical infrastructure, such as power grids and emergency services, faced a "real and credible" threat of cyber attack.