The World Trade Center on September 11, 2001
International terrorism refers to terrorism that goes beyond national boundaries in terms of the methods used, the people that are targeted or the places from which the terrorists operate.
Since the emergence of Al Qaida in the 1990s, international terrorism has become largely synonymous with Islamist terrorism. Terrorist groups in Syria and Iraq, including Al Qaida and the Islamic State of Iraq and the Levant (ISIL), possess both the intention and the capability to direct attacks against the West. The UK is a high-priority target for Islamist extremists and they pose a significant threat to our country and to our interests and citizens abroad. Despite the current main focus on terrorism originating from Syria and Iraq, the threat of terrorism also emanates from other parts of the Middle East and regions such as North, East and West Africa, South and South East Asia.
The majority of terrorist attack plots in this country have been planned by British residents. There are several thousand individuals in the UK who support violent extremism or are engaged in Islamist extremist activity. British nationals who have fought for extremist groups overseas continue to return to the UK, increasing the risk of terrorist attacks. Using skills acquired overseas, they may organise attacks under direction from outside the UK, or on their own initiative, or they might radicalise others to do so. While the majority of returners will not mount attacks in the UK, the large numbers involved mean it is likely that at least some of them will attempt to do so.
Groups like ISIL make full use of social media and modern communication methods to glamorise their horrific acts and inspire others to commit them. Once inspired, an individual might decide to conduct an attack in the name of Islam without any prior signs of radicalisation. Simple, self-organised attacks by UK-based Islamist extremists have increased and are inherently harder to detect than more complex and ambitious plots.
Not all extremist activity is direct attack planning. UK-based Islamist extremists are supporting terrorism by:
The threat is constantly developing, presenting major challenges for the UK's intelligence agencies and the police.
MI5 has undergone major changes in response to the development of the terrorist threat. The resources of all three of the UK's intelligence agencies have been significantly increased since 2001 and we have nearly doubled the number of our staff over the last decade. This allows us to do much more work on a range of issues. We have shifted extra resources into investigating international terrorism. Around 81% of MI5's resources are now used to support our anti-terrorist work. We have greatly improved our ability to work at both national and regional level by setting up a network of stations around the country. In addition, the UK security and law enforcement agencies, including all of the various regional police forces, maintain a close working relationship. This has enabled us to prevent a significant majority of major terrorist plots and regularly disrupt ongoing terrorist activity.
However, as former Director General Sir Jonathan Evans has noted, "risk can be managed and reduced but it cannot realistically be abolished".
More about our response can be found under How we work.