550 Brussels  - Four years ago almost to the day, Estonia became the smallest country to join NATO since 1949, increasing the number of soldiers the alliance commands by approximately 0.1 per cent.

On Wednesday, the tiny Baltic nation (population 1.3 million) is set to prove that size doesn't always matter as it leads NATO into the world of internet-based warfare.

"Estonia is better than many other NATO countries at this, so others can send people there to learn," one NATO expert on new forms of warfare told Deutsche Presse-Agentur dpa to explain why the alliance's smallest newcomer has become its biggest asset.

A year ago, Russian hackers launched a concerted attempt to crash the websites of Estonian government ministries and banks. Their aim was to punish the country for relocating a Soviet-era war memorial.

But ironically, the effect of the attack was to push cyber-defence to the top of the military agenda. And Tallinn's successful resistance earned it a worldwide reputation for web-based warfare.

"Estonia first proposed the idea of a cyber-defence centre in 2004. If it hadn't been for the attacks last year, I'm not sure so many countries would be interested now," one Estonian diplomat told Deutsche Presse-Agentur dpa.

Wednesday's ceremony will see Estonia sign a deal with six other NATO members - Germany, Italy, Spain, Slovakia, Lithuania and Latvia - to upgrade its Tallinn cyber-defence HQ to a "NATO centre of excellence" staffed by experts from the signatory states and the US, and dedicated to studying every aspect of web warfare.

Officially, the expanded centre will not be under direct NATO command, since alliance rules are very strict on the division of responsibilities between member states and the central organization.

But effectively, it brings the entire alliance a step closer to answering the crucial question of how to defend web-based resources, from government communications and military secrets to personal banking and email, against attack.

Indeed, far from just working for the seven signatory countries, the centre's mission is explicitly to "enhance the cooperative cyber-defence capacity of NATO and NATO nations," a document inviting other NATO members to join the service says.

In practice, Wednesday's agreement will see around 15 experts from the signatory states, and the US, moving to Tallinn to work on major issues of web security with an equal number of Estonian colleagues.

In the imposing stone surroundings of Estonia's cyber-HQ, they are to discuss how NATO should respond to web attacks, how to train the next generation of cyber-warriors and how to deal with new threats.

And they are also set to discuss what lessons NATO members can draw from past conflicts - a question which, since the 2007 cyber war, has come to be widely seen as Estonia's particular expertise.

Indeed, while Estonia mooted the idea of a cyber-defence centre almost as soon as it joined NATO, it was not until the summer of 2007 - soon after the attacks - that alliance heavyweights such as the US, Germany, Italy and Spain decided to sign up to the project.

Their participation gives Estonia's cyber-defence centre a significance which goes far beyond its traditional allies within NATO, such as Poland and its Baltic neighbours.

And it is the clearest example yet of how even the smallest and newest NATO members are learning to use the alliance to strengthen their defences - and how, in return, the alliance is using their expertise to help strengthen its own. (dpa)