Terrorism Threats to the UK
UK Threat Level from International Terrorism 2006-2018
Transatlantic aircraft (liquid bomb) plot
10 August 2006
Glasgow Airport attack
30 June 2007
Manchester Arena attack
23 May 2017
Parsons Green attack
15 Sept 2017
Transatlantic aircraft (liquid bomb) plot
10 August 2006
Glasgow Airport attack
30 June 2007
Manchester Arena attack
23 May 2017
Parsons Green attack
15 Sept 2017
2006 Interact with the graphic to find out more about the events that caused the threat level to become CRITICAL. 2017
Critical
Severe
Substantial
Moderate
Low

Threat level

The Joint Terrorism Analysis Centre (JTAC) assesses that the threat from international terrorism to the United Kingdom (UK) is SEVERE, meaning an attack is highly likely. MI5 assesses that the threat from Northern Ireland-related terrorism to Great Britain is MODERATE, meaning an attack is possible, but unlikely.
Last year the UK threat level was twice raised to CRITICAL, meaning an attack was imminent. This represents 46% of the time the country has spent at CRITICAL since the threat levels were made public in 2006.
Andrew Donaldson's profile picture
Andrew Donaldson
Deputy Head of Risk Analysis
Pool Re

Key Actors

Islamist extremists

Islamist extremists are the principal threat to the UK. Daesh and AQ associates remain the key threat actors and likely targets are police, military and Government personnel and crowded places associated with iconic sites and the transport sector. Crowded places represent an opportunity for causing mass casualties, and the transport sector is a favoured target amongst Islamist extremists. Civil aviation remains a desired target, with the 2015 bombing of Metrojet Flight 9268 from Sharm el Sheikh triggering a new wave of aviation themed plots, reminding the Western world that security protocols were not infallible.
Case study
The Afghan connection
International terrorism from the 1980s was heavily shaped by those involved in, or influenced by, the various conflicts in Afghanistan, which attracted fighters from the Middle East and Central and South Asia especially.
During the 1990s, Afghanistan became a haven for extremists to train, develop strategies and form international alliances; veterans of the conflicts in Afghanistan also fought in the Algerian civil war, in Bosnia and Chechnya and carried out terrorist attacks internationally. Some veterans subsequently sought asylum in the UK, where the combination of extremists from different regions with a variety of experiences and skills helped shape the contemporary Islamist threat to the UK.
AQ’s weakened position in Afghanistan post-9/11 was a significant setback to the group. It retained, however, well established extremist networks which were regenerated to some degree in 2015 with their pledge to Taliban Mullah Akhtar Mansour, subsequently amplified by Hamza bin Laden. Mansour also at the time attempted to resist the Daesh recruitment drive which was starting in Afghanistan.
With the fall of the so-called Caliphate in Iraq and Syria, Afghanistan represented a logical option for many Daesh assets to resettle and once again recruit from established extremist networks. That capability is represented in IS-Khorasan (ISKP), which international coalition forces recognise as a threat to their national security and whose senior leaders have been targeted in military action, including air strikes. Despite that action, Afghanistan is likely to re-emerge as a source of global terrorism as an operating base for both AQ and Daesh. Considering the historical links from the country to the UK, an increased role in UK attack plots should be expected in the future.
There were four successful Islamist extremist attacks in 2017 in the UK and the investigation into those attacks and the numerous disrupted plots are likely to have impacted upon the capabilities of both lone actors and extremist networks in the UK. Additionally, the attacks are likely to have reduced the threshold for risk the CT police and MI5 have in counter terrorism investigations. As such, it is probable that plots will be disrupted in far more immature stages which are likely to result in convictions for offences which carry a shorter custodial sentence. This shortened cycle of conviction, custodial sentence and release of terrorist prisoners is likely to compound the domestic terrorist threat. The severity of the UK threat is unlikely to reduce over the next two years. The latest official statistics1 on terrorism arrests in 2018 show a 22% reduction on 2017; this may be accredited to the large number of arrests made in response to the Manchester and London attacks which accounted for a significant number of the 2017 arrests. With that in mind, 351 arrests for terrorism-related activity is still comparatively high and Islamist extremism accounts for both the majority of the arrests and 82% of the total terrorism prison population.
It is probable that plots will be disrupted in far more immature stages which are likely to result in convictions for offences which carry a shorter custodial sentence.
Quote style
Case study
Released Prisoners
“The long term management of terrorist offenders is critical to our ongoing responsibility to keep the public safe”
Quote style
Assistant Commissioner Specialist Operations Neil Basu QPM,
National Lead for Counter Terrorism Policing, 2018
With currently over 650 active terrorist investigations in the UK, unprecedented demand is being placed on the CT police and MI5. The attacks in London and Manchester in 2017 are likely to influence the amount of risk a Senior Investigating Officer is willing to take, so more plots disrupted earlier should be expected. This is likely to mean convictions for lesser terrorism offences, meaning shorter custodial sentences. For the second year running, the largest proportion of terrorist sentences were under four years (accounting for 41% of sentences, 37 of 90 convictions). These convicted terrorists, subject to time spent whilst on remand, could be released back into the community after as little as 12 months. This is likely to compound the UK terrorist threat considering the measures and monitoring required when they are released.
There are a number of measures available to manage and monitor terrorists when released into the community, or those who cannot be deported or prosecuted. Terrorism Prevention and Investigation Measures (TPIMs) offer one option, with (according to official statistics2) at least seven currently in place within the UK. An aspect of TPIMs is the capability to relocate the subject a maximum of 200 miles from their residence. Considering the contribution extremists from East London and East Birmingham make to the UK threat, the 200 miles radius from these locations represent areas of particular counter terrorism concern and threat.

Northern Ireland related terrorism (NIRT)

In March 2018 MI5 reduced the threat level from NIRT to Great Britain to MODERATE, meaning an attack was possible, but unlikely. This indicates that whilst some degree of hostile intent may remain within dissident republicans to attack the mainland, they currently lack the capability to do so or there has been an absence of active attack plans. The case of Ciaran Maxwell, the former Royal Marine convicted of terrorism offences and his suspected affiliations with the Continuity IRA (CIRA) appear an isolated incident although a stark reminder of both the military grade weapons which dissident republicans have available and how police, military and Government personnel are the likely focus of any attention. NIRT remains extremely active in Northern Ireland, with attacks highly likely and the New IRA representing the most significant threat.

Extreme Right Wing

The threat from XRW groups to the UK is growing. In 2017 there was one XRW attack, targeting people leaving Finsbury Park Mosque, and since March that year there have been at least four disrupted XRW attack plots, accounting for around 24% of disrupted plots in the UK. Arrests and custodial sentences for XRW activity in the UK have also steadily increased over the past three years. Latest official statistics state 13% of terrorist prisoners hold XRW ideologies, representing 28 people and an increase from 10 people in the previous year.
The greatest XRW threat to the UK is the proscribed organisation National Action, described by Assistant Commissioner of Specialist Operations Neil Basu QPM as the first XRW group to represent a national security threat. The presence of many serving military personnel within National Action compounds the threat they pose, given their training and access to firearms and explosives, all of which indicate the severity of such attacks may increase.

Assessment

Islamist extremist attacks are highly likely to continue and, considering the diminished role of the so-called Caliphate in Iraq and Syria and disrupted communications from senior leaders there, attackers within the UK are less likely to have received specific instructions from overseas. Attackers are more likely to be inspired by a general Islamist extremist rhetoric. Likely targets are police, military and Government personnel and sites, along with crowded places associated with iconic sites and transport. XRW activity is likely to continue and probably increase, and violence directed towards the Muslim community using vehicles and military grade weapons cannot be ruled out.

UK Attack Methodology scale

The methodology of attacks may be wide ranging, with low complexity attacks using knives and vehicles as weapons being the most probable. The use of improvised explosive devices is likely to continue, particularly those incorporating TATP (Triacetone Triperoxide) above any other homemade explosives. The acquisition and use of firearms cannot be ruled out and remains a significant risk.
Likelihood of attack method
Attack Methodolgy spiral chart