Leading article: A serious cyber threat

There is little doubt that the co-ordinated online attack targeted at a Georgian blogger last week – which had the effect of temporarily bringing down Facebook, Twitter and LiveJournal – was politically motivated. Rather more uncertainty, though, surrounds the contention of the blogger in question that the Kremlin was responsible for the disruption.

We need to be cautious of taking this accusation at face value. No evidence of official Russian involvement in this attack has been uncovered.

Yet this is not the first time a state has been accused of engaging in "cyber warfare". China was accused of hacking into the servers of Western governments in 2007. North Korea is believed to have attacked South Korean computers earlier this year. And Russia itself has form, having been fingered for attacking networks in neighbouring Estonia two years ago.

Whatever the truth of these claims, online security is an area to which governments, including our own, need to pay serious attention. A remarkable amount of sensitive information is held on government servers nowadays, as the case of Gary McKinnon, who managed to hack into 97 US military and Nasa computers, demonstrates.

And it is not just military secrets that are vulnerable. Computer networks are increasingly used to control power plants and transportation systems. Banks and stock markets are similarly dependent on online networks. And, of course, governments are also putting ever more of the private information of their citizens on to vast computer databases.

There is clearly potential here for rather more serious damage than a temporary disruption of Facebook. Governments - and we as citizens - need to ensure that our defences are up to scratch. Even if hostile governments are not the threat they are portrayed as, the potential for organised criminals to compromise these networks provides ample reason for action.

The internet brings great commercial and administrative advantages to governments and private individuals. But it also brings new potential dangers. This week's cyber disruption is a timely reminder of that.