MI5 chief warns AI could help terrorists develop bioweapons

MI5 Director General Sir Ken McCallum used his annual threat speech to warn that the UK has entered a new era of national security. In a rare public appearance, he said artificial intelligence is already changing the threat picture and that the most serious future risk could be its use in biological weapons.

He said AI is supercharging the cyber security contest between attackers and defenders. It can produce propaganda and radicalising material tailored to individuals. MI5 has caught terrorists seeking to exploit AI to improve reconnaissance and attack methods, and AI-enabled drones add a new twist. He said the misuse case he weighted most heavily was AI's potential to change the stakes on existing or even new bioweapons. That has not happened yet, but he said sober work is needed now to prepare for the possibility that AI could help dangerous knowledge reach people who mean harm, or be used to generate new pathogens.

MI5 has set up an AI Threat Assessment Centre, known as ATAC, to assess these risks. It will draw in experts from across the intelligence community, as well as GCHQ, the AI Security Institute and international partners. McCallum also warned about super intelligence, or AI that could outthink humans, saying prudent measures are needed to defend against future possibilities.

On state threats, he said MI5 is now devoting more resource to countering them than during the Cold War. The state threats caseload has quadrupled over the last decade. The National Security Act is in heavy use, with dozens of arrests in the three years since it came into force. Russia remains aggressor number one. Iran and China are also major concerns. The threats include sabotage, arson, cyber attacks, mysterious drones and attempts to undermine democracy, often below the threshold of conventional armed attack. Hostile states often use criminals recruited on the dark web.

Iran was a particular focus. McCallum said more than 50 Iran-linked arrests had been made in the UK in the last year. He pointed to attacks on Jewish communities, including arson attacks, and to a suspected plot against RAF Fairford. The Prime Minister has said that plot was highly likely to have been coordinated by Iran. The IRGC has been proscribed. McCallum expressed solidarity with British Jewish communities.

He also addressed claims about Russian interference in the 2016 Brexit referendum. He said Russia had waged a media and online trolling campaign, and that attempts to sow division continue. But he said the result of the referendum was not in dispute.

Terrorism has not gone away. MI5 continues to see groups planning and inciting attacks, including ISIS and al-Qaeda inspired plots. Far-right extremism is a growing concern, with anti-Muslim and anti-immigration views tipping into terrorist intent. He said MI5 was investigating a radicalised 13-year-old. Targets include synagogues, mosques and immigration centres. There is also concern about violence against politicians, following the murder of Reform politician Ann Widdecombe.

McCallum said national security is now a shared challenge. He called for greater public resilience and awareness. He said threats can appear in subtle ways, such as foreign spies posing as online recruiters or signs in classrooms and workplaces. He said the public should not be cowed or intimidated, but should help detect threats and keep the country functioning and united.

Experts and political figures responded. Some said the biological risk is serious because biology is dual use and AI could help create digital designs for more transmissible or lethal pathogens. They warned about synthetic DNA, automated labs and weak guardrails on some AI models. Others said AI is already helping militant groups with practical tasks. The Russian embassy rejected McCallum's claims, saying attributing every cyber incident and criminal case in Europe to Moscow is convenient and baseless. The government has pointed to the new AI threat assessment centre as part of its response.