By Frank Gardner
BBC Security Correspondent, Norway
Housed in a shallow valley just outside Oslo is the Norwegian Defence Research Institute.
It is an unremarkable place to look at, but inside sits one of Europe's leading teams of researchers into the growing phenomenon known as "online Jihadism", or al-Qaeda-inspired extremism on the internet.
Propaganda is the primary purpose of using the net, say researchers
They are neither intelligence agents nor soldiers, but academics who use their fluent Arabic to produce unclassified research.
Like many who study this subject, they disguise their real identity by using false Arabic names and proxy addresses.
Brynjar Lia, a senior team member and author of an acclaimed book about terrorism and the internet, says al-Qaeda and its affiliates use the internet for several purposes.
Training for interrogations
"Propaganda, calling people to jihad, is the primary purpose," he said.
"It has always been like that from the beginning, but secondly it is to communicate to the internal community of jihadis with the message to continue to fight and build up the spirit of combat, and also internal communication with cell members and so on.
"This can be via e-mail or encrypted messages. Usually they don't use much encryption, they only use easy codes, simple codes that can be read by people but interpreted as something that doesn't have anything to do with terrorism.
"Then there is also the external audience, those enemies who they want to frighten and terrorise.
"The idea is to produce videos that are very scary, like decapitations and other similar movies.
"Then there is also the electronic jihad part of it, which is to destroy enemy websites which are critical of the jihadi movement.
"The last area is training. That could be anything from providing security instructions, how to withstand interrogations, how to evade surveillance but it could also be how to produce explosives, how to put together a mine, how to place the mine and so on."
In the last year, say the Norwegian analysts, the jihadists have been adapting their online recruiting efforts to target audiences in Europe, including Britain.
Videos of speeches, such as those by al-Qaeda chief strategist Dr Ayman al-Zawahiri, now come with English subtitles.
One of the areas where jihadist propagandists have been most successful and innovative is in targeting the youth market
Al-Qaeda's Californian-born spokesman Adam Gadahn addresses Western audiences in American English, drawing attention to what he sees as the hypocrisy of Western civilisation.
Other jihadi videos are being dubbed into German, Spanish, Swedish and other European languages with the aims of both attracting potential recruits and intimidating those seen as the enemy.
Other innovations include increasingly high quality film footage, fresh from the battlefields of Iraq or Afghanistan, and sophisticated instructions on bomb-making and weapon handling.
But one of the areas where jihadist propagandists have been most successful and innovative is in targeting the youth market, reaching out to teenagers and young men through internet chat rooms in cyberspace.
Their attention is grabbed by catchy videos like the 2004 rap hit Dirty Kuffar by Sheikh Terra, online games where points are scored by simulating attacks on US soldiers with the click of a mouse, and even a video equating goals scored in the World Cup with improvised bomb attacks on coalition forces in Iraq, accompanied by tumultuous applause.
Thomas Hegghammer from the Norwegian Defence Research Institute describes how al-Qaeda sympathisers log onto certain internet forums to discuss the films and the latest news from Iraq, Afghanistan and elsewhere, always trying to stay one step ahead of the authorities.
"These forums are like the sort of town square of online jihadism, it's where people meet to collect information and discuss topics," he said.
"If you look at the address it's quite anonymous, it's just numbers and this is because they move around all the time to avoid hackers and government agencies that try and take them down, so some of these sites more around on a weekly basis or even daily basis and the way you find these addresses is from other forums.
"So there is always a redundancy. So if one forum is shut down then you go to the other one to get the new address."
Western governments have been slow to wake up to the enormous potential for jihadists to recruit over the internet, but British officials now believe that, after face-to-face meetings, the internet has become the prime means of radicalisation and recruitment.
The problem has been urgently debated at this week's meeting of European security and interior ministers in Stratford-upon-Avon.
"The home secretary takes it very seriously," said a Home Office official, adding: "We are engaged in a battle of ideas and values."
But one London-based Arab journalist who monitors online jihadism contends that the British government is essentially passive when it comes to the wave of jihadist propaganda out there on the internet.
Camille Tawil said: "I believe the British have been happy just to monitor the internet.
"My impression is that they believe it's a lost battle to counter the al-Qaeda message on the internet.
"The Americans however have been a little bit ahead of the British in countering that message.
"What they do is they have people who pretend to be Islamic militants trying to lure some people from al-Qaeda or extremists into saying something, and that would lead to their arrest - however in Britain we haven't seen anything like this.
"The Americans are well ahead of the British in this."
British government officials deny they are doing nothing, but not surprisingly they decline to discuss anything to do with secret intelligence operations.
"We are doing a number of things, some overt and some covert," says the Home Office official, adding with a degree of weary candour: "But we admit some of them are not working".