The Glass Doors of Thames House: A Diagnosis of Chronic Threat

Sir Ken McCallum, Director General of MI5, delivered his annual threat update at Thames House on October 13, 2026, declaring that the United Kingdom had entered a new era of national security [1]bbc.comMI5 tackling more state threats than during Cold War, warns intelligence chiefSir Ken McCallum said threats from foreign adversaries had quadrupled in the last decade, with Russia 'aggressor number one' as well as increased Iran-linked aggression against Jewish sites and military bases.Open source ↗[7]metro.co.ukMI5 chief says UK will handle AI threat like tackled al Qaeda 9/11He said it involves the rising dangers of hostile states – with more MI5 resources devoted to countering those threats than during the Cold War – and more opaque risks from artificial intelligence.Open source ↗[10]mi5.gov.ukMI5 Director General Delivers Annual Threat UpdateHe stated that we have entered a new era of national security requiring a new response. Resources spent on tackling state threats from hostile nations such as Russia, Iran, and China, has quadrupled in the last decade and is now greater…Open source ↗. This was not a warning of an impending apocalypse. It was a diagnosis of a chronic condition. The stakes were clear: the UK’s social cohesion, democratic institutions, and physical infrastructure were under simultaneous assault from powerful states and sophisticated non-state actors. MI5 is now devoting more resource to countering state threats than during the Cold War, while preparing for opaque technological risks for which, in McCallum's words, human history has given us no experience [7]metro.co.ukMI5 chief says UK will handle AI threat like tackled al Qaeda 9/11He said it involves the rising dangers of hostile states – with more MI5 resources devoted to countering those threats than during the Cold War – and more opaque risks from artificial intelligence.Open source ↗[10].

Escalation of State Threats and Hybrid Warfare

The most significant change in the threat landscape is the exponential growth in state-sponsored hostility. McCallum stated that threats from foreign adversaries had quadrupled in the last decade [1]. This surge has forced MI5 to devote more resources to countering state threats than during the Cold War [7][10]. The intelligence service’s caseload for state threats has expanded dramatically [10].

Russia remains the primary focus of this concern. McCallum designated Russia as "aggressor number one" in the context of threats to the UK [5]sacbee.comFactbox-MI5 chief lists Iran, Russia, AI and terrorists among threats to UKLONDON, Oct 13 (Reuters) - MI5 spy chief Ken McCallum delivered his annual speech on Tuesday outlining his view of the threats to Britain, from hostile states such as Iran and Russia to the development of artificial intelligence. McCallum…Open source ↗[8]ndtv.comIran, Russia, AI, Terrorists: MI5 Chief Flags Threats To UKKen McCallum called Russia, which denies involvement in hostile acts in Britain and other Western countries, 'aggressor number one'. He said it was escalating 'hybrid' warfare.Open source ↗. He described the Kremlin as continuing to lash out at the UK and its allies through various channels [9]thesun.co.ukGrowing risk of terrorists using AI-made bioweapons to attack UK & inventing deadly new pathogens, MI5 chief warnsBritain's security services are fighting to stop terrorists from creating new bioweapons with AI, the head of MI5 has revealed. Sir Ken McCallum said that of all the future threats from new technology, one he is focused on is terror…Open source ↗. However, he noted that Russia’s traditional covert footprint has been significantly weakened by the expulsion of nearly 1,000 officials from embassies since the invasion of Ukraine [1]. This reduction in capability has compelled Moscow to rely more heavily on criminal proxies and native volunteers to execute hostile acts [5].

McCallum warned that both Tehran and Moscow are seeking to escalate hybrid warfare campaigns against Britain [6]ft.comKen McCallum warns that both Tehran and Moscow are seeking to escalate hybrid warfareKen McCallum warns that both Tehran and Moscow are seeking to escalate hybrid warfare, with state threats quadrupling in a decade.Open source ↗. These tactics are designed to stay below the threshold that would trigger a direct NATO response [5]. Hybrid attacks include cyber-attacks, sabotage, and misinformation efforts aimed at unsettling European nations [1]. The goal is to intimidate adversaries and test their resolve without triggering a full-scale military retaliation [9].

Iran has similarly expanded its hybrid campaign in the UK. McCallum reported that operations connected to Iran have yielded more than 50 arrests in the last year [5]. Much of this aggression has been directed at Jewish communities, but there is also a shift toward targeting harder assets such as military sites [8]. The intelligence chief said Iranian ambitions now extend to harder targets, like military sites [9]. This expansion indicates a more aggressive posture by Tehran in using criminal proxies to intimidate opponents and advance its interests within the UK [6].

Intelligence Response and Investigative Metrics

The increase in state threats has translated into tangible operational metrics for MI5. McCallum reported that there had been a 35% increase in the number of individuals investigated for involvement in state threat activity over the last year [3]wral.comMcCallum also said there had been 'more than 20 potentially lethal Iran-backed plots' in the past yearMcCallum also said there had been 'more than 20 potentially lethal Iran-backed plots' in the past year. 'State threats are increasing. ... In the last year, we've seen a 35% increase in the number of individuals we're investigating for…Open source ↗. He described state threat activity as overwhelmingly dominated by Russian, Chinese and Iranian state actors [3].

McCallum emphasized that these individuals are present in the UK rather than directing operations from overseas [3]. This localization of threats requires a more robust domestic policing and intelligence framework. The National Security Act, introduced in 2023, has been employed heavily to tackle these threats, resulting in dozens of arrests since its enactment [10]. The law, a 2023 measure designed to target people working against UK interests for foreign powers, has been used against threats from China as well as Iran and Russia [1]bbc.comMI5 tackling more state threats than during Cold War, warns intelligence chiefSir Ken McCallum said threats from foreign adversaries had quadrupled in the last decade, with Russia 'aggressor number one' as well as increased Iran-linked aggression against Jewish sites and military bases.Open source ↗.

The intelligence chief also noted that MI5 successes in identifying and expelling Russian spies have left the Kremlin dependent on paying proxies for attempted attacks [1]. McCallum stated that those who seek to cause mayhem on British streets, whether hired thugs or their paymasters overseas, will meet an unflinching response [1].

The Role of Artificial Intelligence in Threat Multiplication

Artificial intelligence represents a distinct category of risk that McCallum described as more opaque than the dangers posed by hostile states [7]metro.co.ukMI5 chief says UK will handle AI threat like tackled al Qaeda 9/11He said it involves the rising dangers of hostile states – with more MI5 resources devoted to countering those threats than during the Cold War – and more opaque risks from artificial intelligence.Open source ↗. He stated that AI is "supercharging the cybersecurity contest between attackers and defenders" [10]mi5.gov.ukMI5 Director General Delivers Annual Threat UpdateHe stated that we have entered a new era of national security requiring a new response. Resources spent on tackling state threats from hostile nations such as Russia, Iran, and China, has quadrupled in the last decade and is now greater…Open source ↗. This technology enables adversaries to produce propaganda and radicalizing material tailored to individuals, enhancing their ability to influence public sentiment and recruit supporters [1]. The precision of such content increases its potential impact on societal cohesion.

McCallum warned that terrorists are seeking to exploit AI to improve their reconnaissance and attack methodologies [5]. One specific concern is the use of AI-enabled drones, which add a new layer of complexity to physical security threats [8]. The intelligence chief noted that MI5 has caught potential attackers attempting to harness AI for these purposes [9].

A more profound concern is the potential for AI to facilitate the development of bioweapons. McCallum identified this as the misuse case to which he attaches the greatest weight [9]. He warned that terrorists could use AI to create new pathogens or enhance existing biological threats, thereby changing the stakes of terrorist attacks [7]. While he acknowledged that this risk is not yet realized, he argued that it deserves serious attention due to its catastrophic potential [9]. The alignment problem, where AI systems might act in ways misaligned with human objectives, presents a novel challenge for which history offers no precedent [8].

To address these emerging dangers, MI5 launched the AI Threat Assessment Centre (AITAC) in 2026 [7]. This center assembles a team from various bodies to produce all-source assessments that separate bluster from reality [10]. The initiative aims to provide government with clear insights into AI risks, enabling consequential choices to be made at pace [10]. McCallum compared the challenge of addressing AI threats to the response required after 9/11, noting that while there was no confident answer initially, the threat was tackled methodically [7]. He emphasized that the UK Intelligence Community is working closely with the AI Security Institute to retain a capability edge against those who mean the UK harm [9].

Terrorism and Societal Resilience

While state threats have grown, terrorism remains a significant concern. McCallum said that MI5's work countering terrorism and state threats is now "pretty much of equal scale" [10]mi5.gov.ukMI5 Director General Delivers Annual Threat UpdateHe stated that we have entered a new era of national security requiring a new response. Resources spent on tackling state threats from hostile nations such as Russia, Iran, and China, has quadrupled in the last decade and is now greater…Open source ↗. The national terrorism threat level was raised to severe in April 2026, indicating that an attack is highly likely [8].

A marked trend in recent months has been the increase in extreme right-wing terrorism. McCallum reported that extremist versions of anti-immigration and anti-Muslim grievances are tipping into terrorist intent [5]. This ideology tends to skew young, driven by online radicalization [9]. MI5 investigated a radicalized 13-year-old extremist, which led to an international partner preventing a lethal attack on their soil [8]. This case illustrates the cross-border nature of modern terrorism and the importance of intelligence sharing.

McCallum called for greater societal resilience as a core component of national security [4]. He argued that national security is not just the concern of specialist agencies but a shared endeavor involving government, business, academia, and the public [4]. The protection of democracy and community cohesion has never felt more vital [10]. Adversaries seek to weaponize social frictions, using trolls and algorithms to divide communities [10]. McCallum warned against playing into adversaries' hands by overstating the effectiveness of their interference, such as in the Brexit referendum debate [5]. He distinguished between attempted interference and achieved outcomes, noting that Russian online trolling had been comparatively unimpressive [9].

Strategic Implications and Future Outlook

The quadrupling of state threats and the emergence of AI risks mean MI5 is devoting more resource to countering state threats than during the Cold War [1]. Its state threats and terrorism missions are now of pretty much equal scale [10].

The reliance on hybrid warfare by Russia and Iran indicates that these states view the UK as a viable target for asymmetric pressure. McCallum characterised Russia's reliance on paid criminals as the mark of a weak toolkit, not of a great power with the strategic upper hand [10]mi5.gov.ukMI5 Director General Delivers Annual Threat UpdateHe stated that we have entered a new era of national security requiring a new response. Resources spent on tackling state threats from hostile nations such as Russia, Iran, and China, has quadrupled in the last decade and is now greater…Open source ↗.

The emergence of AI as a threat multiplier introduces uncertainties that challenge traditional security frameworks. The potential for bioweapons development and autonomous drone attacks represents a qualitative shift in risk [9]. McCallum’s comparison to the post-9/11 era suggests that the response will require innovative structures and international collaboration, such as the Five Eyes alliance [8]. The launch of AITAC is a step toward managing this uncertainty, but the rapid evolution of AI technology means that assessments must be continuously updated.

The intelligence chief’s judgment is that the UK has entered a new era of national security that requires a new response from MI5 and the country [10]mi5.gov.ukMI5 Director General Delivers Annual Threat UpdateHe stated that we have entered a new era of national security requiring a new response. Resources spent on tackling state threats from hostile nations such as Russia, Iran, and China, has quadrupled in the last decade and is now greater…Open source ↗. While MI5 has strengthened its response, the challenges posed by Russia, Iran, and AI are persistent and evolving. The agency’s focus on proactive disruption and resilience building reflects an acknowledgment that complete prevention is unlikely. Instead, the goal is to mitigate impact and maintain national security in a contested environment. This approach requires sustained investment and political will to address the root causes of instability and the technological advancements that empower adversaries.

The warnings issued by Sir Ken McCallum serve as a call to arms for all sectors of British society [4]. The integration of national security into everyday life means that individuals must remain vigilant against manipulation and radicalization. The intelligence community’s role is to provide early warning and strategic insight, enabling the government and public to respond effectively. The future of UK security depends on balancing robust defense measures with the preservation of democratic values and social trust.