MI5’s new security doctrine puts resilience on the front line

In his annual threat update, Director General Sir Ken McCallum described a security environment in which hostile states, terrorists and emerging technologies can disrupt businesses and communities as readily as government.

Sir Ken McCallum’s annual threat update, delivered on 13 October, set out a change in how MI5 sees its work. The service now treats Protect as a core mission alongside counterterrorism and countering state threats. Its purpose is to make the UK harder to attack and better able to function when an attack succeeds.

McCallum’s argument was that national security can no longer be left chiefly to intelligence agencies. Financial systems, energy networks, supply chains and communications platforms are exposed to disruption. So are the people and organisations that depend on them. He organised the resilience challenge into three connected areas: the systems on which the country runs, the cohesion of its communities, and its ability to manage technological change.

Hostile states are using wider means

MI5’s state-threat caseload has quadrupled over the past decade. McCallum said the service now devotes more resources to it than it did during the Cold War, while its operational work on state threats and terrorism is roughly equal in scale. Russia remains, in his assessment, the leading state aggressor. He described a campaign of cyberattacks, sabotage and attempted violence intended to exert pressure below the threshold of direct conflict with NATO.

He also described a change in how Russia operates. Following the expulsion of almost 1,000 members of its traditional covert presence since the invasion of Ukraine, Moscow has increasingly turned to criminals and willing volunteers. For defence firms, energy companies and operators of critical infrastructure, his advice was direct: apply existing guidance on sabotage, drones and cyber threats before an incident occurs.

Iran was the second major focus. McCallum said Iran-linked operations had led to more than 50 arrests in the UK over the preceding 12 months. He described continued threats against Iranian opposition figures, media organisations and Jewish communities, as well as an apparent ambition to target harder sites, including military facilities. He limited his comments on particular cases because investigations and possible prosecutions remain live.

On China, the emphasis was espionage, coercion and interference. McCallum pointed to recent warnings about attempts to reach researchers and officials through research bodies, cover companies and professional networks. He also argued for proportionate decisions: valuable international partnerships can continue when organisations understand and manage the associated risks.

Terrorism remains a major pressure

The growth in state threats has not displaced terrorism. McCallum noted that the UK terrorism threat level had recently returned to SEVERE, meaning an attack is highly likely. Islamist terrorism remains a concern, while the recent increase in the threat level was driven in significant part by extreme right-wing terrorism. He highlighted cases involving anti-immigration and anti-Muslim grievances that had developed into plans for violence. Some of those investigated were teenagers radicalised online.

That connection between online activity and physical harm ran through the speech. McCallum warned that hostile actors seek to exploit social divisions, while algorithms can intensify the material people encounter. His concern was not confined to false information itself. It was also the effect of manipulation on public confidence, community relations and, in the gravest cases, individual behaviour.

AI adds another dimension

McCallum said AI is already changing the contest between cyber attackers and defenders. It can also produce propaganda tailored to individuals. MI5 has encountered terrorists seeking to use it to improve reconnaissance and attack methods, while AI-enabled drones present a further challenge. He identified AI’s potential to assist with existing or new biological weapons as a serious future risk, while making clear that this particular misuse has not yet been realised.

MI5 has established an AI Threat Assessment Centre to examine these risks with expertise from across government. Its task is to distinguish credible developments from inflated claims so that decisions can keep pace with the technology.

What the speech means for organisations

McCallum’s central message was preparedness. For businesses and institutions, the speech points to a practical need to connect security, technology, communications and continuity planning. An attack on a supplier, an employee, a facility or an information system can quickly become a test of public confidence as well as operational capability. That is an implication of his assessment, rather than a separate threat category announced by MI5.

The stronger organisation is one that knows where it is exposed, can identify a developing incident, and can continue to operate and communicate when pressure arrives. MI5’s decision to put protection beside its two established missions shows how central that capacity has become.