MI5 chief warns Iran is targeting military sites in UK as hostile state threats surge

Iran is accused of expanding its targets in Britain beyond opponents of its Islamic authorities. MI5 chief Ken McCallum said Tehran was increasingly interested in “harder targets”, including military sites. The concern matters because such sites support military operations and may attract retaliation or disrupt local communities.

At RAF Fairford in western England, residents were evacuated on September 27. Armed police and army bomb-disposal experts searched the area. Police found petrol, an accelerant, in three vans, but no explosives. Seven men in their twenties were arrested and later released on bail under investigation. British authorities linked the incident to Tehran, and Andy Burnham said it was almost certainly directed by Iran’s Revolutionary Guard.

Iran denied involvement. The suspected plot led the US to remove its bombers from RAF Fairford. McCallum said the incident was not unique, suggesting British officials see it as part of a wider pattern of Iranian activity against military sites.

MI5 is the United Kingdom’s domestic security and intelligence service. Its work focuses on identifying and disrupting threats to national security within Britain, including terrorism, espionage and hostile activity by foreign states. The article presents MI5 as a central agency in responding to a changing security environment.

Its chief, Ken McCallum, described investigations into suspected Iranian plots and wider state threats. MI5 helps assess intelligence, coordinate with police and identify possible attacks before they happen. The article also says its work countering threats from Russia, Iran and China has quadrupled over the past decade.

That expanded workload reflects what McCallum called a “new era of national security”. He said Russia and Iran were increasing hybrid warfare campaigns, while artificial intelligence was accelerating cyber threats. MI5 has created an AI Threat Assessment Centre to study and respond to emerging risks, including AI-assisted attacks and possible biological dangers.

Iran’s Islamic Revolutionary Guard Corps, commonly called the Revolutionary Guard, is a powerful Iranian military and security organisation. Proxies are separate armed groups or networks that receive support, direction or resources from a government while operating under their own names. The article does not provide a full organisational description, but it links Iran’s Guard and proxies to activity abroad.

Indirect action can help a government apply pressure while obscuring who planned or ordered an operation. Proxies may conduct sabotage, arson, surveillance or attacks, using local access and avoiding an obvious deployment of Iranian forces. Britain says Iranian proxies carried out arson and sabotage attacks on Jewish sites. Andy Burnham said the Fairford plot was almost certainly directed by the Revolutionary Guard.

Iran denies involvement in the Fairford case. However, McCallum said Tehran’s ambitions were moving beyond traditional targets, such as Iranians opposed to Iran’s Islamic authorities, toward military sites. He said similar examples had occurred outside the UK as well.

MI5’s work countering threats from states has quadrupled over the past decade. The agency’s chief, Ken McCallum, identified Russia, Iran and China as the main state-based sources of concern. That figure signals a major expansion in the scale of Britain’s counterintelligence and security challenge.

The article connects the increase to several forms of activity. Russia and Iran are said to be expanding hybrid warfare campaigns against the UK. Iran is also accused of targeting Jewish sites and seeking access to harder targets, including military facilities. The suspected activity ranges from arson and sabotage to possible reconnaissance and attacks.

McCallum described Britain as entering a “new era of national security”. Technology is adding another layer, especially as artificial intelligence strengthens both attackers and defenders. MI5 has responded by creating an AI Threat Assessment Centre, while continuing to investigate suspected plots and assess threats from foreign governments.

An attack on a UK military site could threaten personnel and nearby residents, interrupt military operations and require a rapid security response. It could also create pressure for stronger protection around bases and raise tensions between Britain, the United States and Iran. The article does not describe a completed attack, so these are potential consequences rather than reported outcomes.

The RAF Fairford incident shows how quickly disruption can occur even without explosives. Residents were evacuated while armed police and bomb-disposal experts searched the area. Petrol was found in three vans, but no explosives. Seven men were arrested and released on bail under investigation. The suspected plot alone affected the base’s operations.

British authorities linked the incident to Tehran, which led the US to pull its bombers from RAF Fairford. The base had been used to bomb Iran during this year’s war. Iran denied involvement, although it has said any base used to attack its territory is a legitimate target.

Hybrid warfare is a campaign that combines military and non-military methods to weaken or pressure another country. It can include cyberattacks, sabotage, disinformation, espionage, economic pressure and the use of proxy groups. The article says Russia and Iran are expanding hybrid warfare campaigns against the UK, but it does not give a complete definition.

A government can act through covert networks or partners rather than openly sending its own forces. That can make an operation harder to attribute and may keep it below the threshold of conventional war. In the article, Britain says Iranian proxies carried out arson and sabotage attacks on Jewish sites. McCallum also described Iranian efforts to reach harder targets, including military sites.

Hybrid warfare creates persistent pressure rather than one declared battlefield. It can force police, intelligence agencies and the military to respond across many areas at once. MI5’s state-threat workload has quadrupled in a decade, as officials confront activity linked chiefly to Russia, Iran and China.

Artificial intelligence could make security threats more dangerous by speeding up tasks that once required specialist time and knowledge. McCallum said AI was “supercharging” the cybersecurity battle. He also warned that AI could change the risks from chemical, biological or radiological weapons. These dangers matter because faster tools can widen access to harmful capabilities.

The article says terror plotters have used AI for reconnaissance and attacks, including AI-enabled drones. Reconnaissance can help identify targets, routes or weaknesses, while automated systems may support an attack. McCallum identified two biological risks: AI could put dangerous knowledge into the hands of people who should not have it, or generate novel pathogens not previously seen.

The article does not report a new pathogen being created. It presents the possibility as a future concern. MI5 has established an AI Threat Assessment Centre to keep ahead of these risks. McCallum said humanity has no experience facing an actor smarter than humans.