How the threat has developed

The international terrorist threat to the UK has evolved considerably in recent years. As of November 2007, the Security Service and police are tracking around 2,000 suspects in the UK, comprising some 200 terrorist networks. Thirty active plots are currently under investigation.

Numbers of suspects under investigation, 2004-2007

These figures have grown substantially since 2000. At the time of the September 11, 2001 terrorist attacks in the United States, approximately 250 individuals in the UK were under investigation in connection with international terrorism. There has been a major increase in the numbers since then: 500 people were under investigation by July 2004, 800 by July 2005 and 1,600 by the end of 2006.

This can be attributed to two principal factors. First, there has been a significant growth in the number of people involved in Islamist extremism. The ongoing conflicts in the Middle East and South Asia have become a dominant issue for extremist groups such as Al Qaida. They have developed increasingly sophisticated methods, in particular using the Internet and videos/DVDs, to promote their propaganda. This has helped to spread extremist ideologies to a worldwide audience.

Second, the police and Security Service have made major improvements in recent years in understanding and tracking the threat. Since 2001, our resources have been significantly increased. This has enabled us to focus more closely on international terrorism and improve our knowledge and visibility of the problem.

As the 2001 figure indicates, the threat was already substantial even before the 9/11 attacks. A number of British citizens were already radicalised at this stage and had travelled to Al Qaida camps in Afghanistan for terrorist training. Some went on to fight alongside fellow extremists in various conflicts, or returned to the UK to set up terrorist networks of their own. Others who remained in the UK provided aid and funding to a variety of extremist causes at home and abroad, including the planning of terrorist attacks.

The UK itself appears to have been a target for international terrorists prior to 9/11. In November 2000, police discovered 70 kg (154 lb) of home-made explosives in a suburban "bomb factory" in Birmingham. Although the intended target was unclear, it is likely that the explosives were meant to be used to carry out terrorist attacks in the UK. Moinul Abedin, a British citizen of Bangladeshi origins, was later sentenced to 20 years' imprisonment for his role in the plot.

The level of activity of extremist groups in the UK increased considerably following the 9/11 attacks and the international military operations against the Taleban and Al Qaida in Afghanistan. The success of the 9/11 attacks brought Al Qaida to worldwide attention and earned it great prestige in extremist circles. A number of radical clerics promoted its ideology in several British mosques. Religious bookshops and the Internet were exploited to distribute extremist propaganda about the 9/11 attacks and international military operations in Afghanistan and Iraq.

At the same time, individuals who had been trained in Taliban-ruled Afghanistan returned to the UK to set up terrorist cells and organise attacks. Newly-radicalised recruits travelled to terrorist training camps in border regions of Pakistan, or to participate in the Afghan and Iraqi insurgencies. This pattern of activity has continued to the present day.

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