Hostile forces on our borders in the battle for cyberspace

But not any more. The Government has identified cyber attacks as one of the four biggest threats to UK security, along with war, terrorism and natural disaster. The first National Security Strategy, published this week, said the London 2012 Olympics would be an "attractive target" for cyber criminals who might try to hack into computer systems causing chaos to events and disrupting critical services.

Cyber crime – with the potential to cause "devastating" damage such as bringing down air traffic control systems or hacking into power station systems – has become a real and present danger, according to those in the know.

Iain Lobban, the director of GCHQ, the Government's electronic spying agency, last week used his first public speech to call for an

aggressive approach to cyber attacks, and warned of the dangers of adopting the sort of defensive strategy famously symbolised by France's Maginot line, which was meant to repel the Germans and failed.

In his speech at the International Institute for Strategic Studies (IISS) he said the UK faces a "real and credible" threat of cyber attack, pointing out that the huge growth of the internet had opened up new vulnerabilities, which could be exploited by both hostile states and criminals. He revealed there were more than 20,000 "malicious" emails on Government networks each month, of which 1,000 were deliberately targeted, while intellectual property theft was taking place on a "massive scale" – some relating to national security.

"Cyberspace is contested every day, every hour, every minute, every second," he said. His views were echoed by Home Office Security Minister Baroness Neville-Jones who described cyberspace as "a new national frontier".

Cyber security has also featured for the first time in the Government's latest Strategic Defence and Security Review, with 500m allocated to bolster Britain's critical national infrastructure from malicious hacking and combat the growing menace of online cyber crime.

Reading all this you could be forgiven for thinking that "we're doomed", as Private Frazer from Dad's Army might say. But just how serious is the threat we're facing?

Dr Stefan Fafinski, of the centre for criminal justice studies at Leeds University, welcomes the fact that the Government is taking the issue seriously. "As more systems become networked, the greater the

potential risks of cyber attacks," he says.

He points out that the cyber threat is nothing new.

"It is a real and present threat now, but it's been on the agenda for a very long time.

"It's good that more investment and more thought is going into

protecting potentially vulnerable systems from a breach, or mitigating the consequences should one occur.

"We have seen this happen in other countries.

"Estonia was the victim of a co-ordinated attack in 2007 and there has also been an alleged attack on one of Iran's nuclear facilities.

"There is certainly evidence that cyber attacks have taken place elsewhere so there are risks to the national infrastructure and to our economy."

Security chiefs in the US have claimed terrorist cyber attacks on government computer systems and businesses could be a latter-day Pearl Harbour.

But Dr Fafinski says these risks need to be put in context.

"Could such an attack be the 'next Pearl Harbour'? Perhaps, but how likely is that to happen? I would say it's very unlikely."

However, no country's national infrastructure can ever be completely secure.

"There has been a lot of time and money spent making our national computer networks as attack-free as possible, but they are always going to be vulnerable to some extent, albeit extremely limited.

"That said, we never hear about attacks which take place but are detected and neutralised with no adverse consequences.

"If terrorists were able to get into key parts of our infrastructure like air traffic control systems and the National Grid, then it could have an enormous impact on the operation of the country, but then so does snow. Bad weather can also cause our infrastructure to grind to a halt, yet we are supposed to have plans to mitigate against that," he says.

"So is there a risk? Yes. Has it been over hyped? Quite probably."