Iran focused on attacking "harder targets," U.K. spy chief warns

“Harder targets” refers to military installations and other locations that are more protected than civilian sites. MI5 chief Sir Ken McCallum said Iran had shifted toward targeting them. The warning matters because it suggests a broader and more ambitious threat to Britain’s national security.

Military sites are difficult targets because they have controlled access, security personnel, surveillance, and other protective measures. The article does not list specific defenses, but it identifies military bases as harder targets than Jewish communities, media organizations, or other civilian locations. McCallum declined to provide details about the installations involved.

One alleged case involved RAF Fairford, a U.K. air base used by U.S. bombers. The incident was thwarted in late September, and the United States moved its long-range bombers afterward. Investigations continue, so the article does not establish exactly how the base was targeted or who carried out the plot.

MI5’s warning followed a series of alleged Iran-linked incidents in Britain and elsewhere in Europe. These included arson and sabotage targeting Jewish communities and other sites. McCallum called them “sickening acts” and said much of the aggression had targeted British Jewish communities.

The Iran-aligned group IMCR claimed responsibility for attacks on synagogues in the Netherlands and Belgium. It also claimed multiple attacks on north London’s Jewish community. A representative said the group would continue threatening U.S. and Israeli interests and urged people to avoid Zionist and American interests.

The alleged threat then appeared to extend toward military sites. Counterterrorism police said an incident near RAF Fairford might involve proxies or individuals knowingly or unknowingly working for a foreign state. McCallum withheld details because investigations were ongoing. The base had been used by U.S. bombers to target Iran.

The reported figures show that Britain is handling a substantial and growing state-threat challenge. More than 50 Iran-linked arrests were made in the United Kingdom over the past year, according to MI5 chief Sir Ken McCallum. The arrests relate to alleged activities connected to Iran, not necessarily proven Iranian government operations.

The wider trend is even larger. McCallum said the number of state-threat cases handled by MI5 had quadrupled over the past decade. He also said MI5 was devoting more resources to countering state threats in 2026 than during the Cold War. That comparison illustrates how seriously the agency views current foreign activity.

The figures cover several threats, including Iran-linked violence and Russia’s alleged hybrid warfare. McCallum called Russia “aggressor number one,” while warning about Iran and other actors. The article gives no breakdown of the arrests, case types, convictions, or individual outcomes, so the numbers measure investigations and arrests rather than final judgments.

Criminal proxies are intermediaries used by a government to conduct hostile activity. Instead of acting openly, a state can subcontract violence or sabotage to criminals, organized groups, or individuals. This can create distance between the government and the attack, while making the operation harder to trace.

McCallum said Iran was using criminal proxies to intimidate oppositionists, Iranian media organizations, and Israeli sites. British counterterrorism police said the RAF Fairford incident might have involved proxies or people working for a foreign state knowingly or unknowingly. In that situation, a person might accept an ordinary criminal task without understanding its wider purpose or sponsor.

The article says Iran, like Russia, has repeatedly been accused of using such individuals across Western Europe. This method complicates investigations and public warnings because authorities must identify both the immediate perpetrators and any state direction behind them. It also allows governments to deny direct involvement while still pursuing strategic pressure.

Hybrid warfare is a mix of hostile activities that fall short of conventional military action. McCallum described it as including cyberattacks, sabotage, and other efforts to pressure or destabilize a country. The approach matters because it can impose costs without crossing the clearer threshold of an open military attack.

The article links Russia to an increasingly aggressive hybrid campaign against Britain and its allies. It says Moscow may be seeking to unsettle European countries while its military progress in Ukraine remains limited and costly. Iran’s alleged use of criminal proxies reflects a similar logic: pressure can be applied through deniable actors rather than uniformed forces.

This creates a difficult security problem. Governments must respond to attacks that may be serious but deliberately ambiguous. McCallum said conventional threats were being managed by military or other colleagues, while Russia, Iran, and others operated beneath conventional armed conflict. That means intelligence, policing, cybersecurity, and diplomacy all become important parts of defense.

Targeting a military installation can affect both immediate safety and military readiness. Personnel may face danger, operations may be delayed, and commanders may need to restrict access or move equipment. The incident can also force governments to divert resources toward protection and investigation.

The article gives RAF Fairford as a concrete example. A suspected plot near the U.K. air base was thwarted in late September. The base had been used by U.S. bombers to target Iran, and the United States moved all its long-range bombers away after the incident. British officials said the event may have involved proxies or people working for a foreign state.

Such an incident can increase international tensions because it links a domestic security event to wider conflict involving Iran, Britain, and the United States. Prime Minister Andy Burnham said the incident was almost certainly directed by Iran’s Islamic Revolutionary Guard Corps. However, investigations were continuing, and MI5 did not provide further details.

McCallum warned that AI is changing security rapidly. It can help attackers find weaknesses, automate malicious activity, and produce convincing material. It can also help defenders analyze threats, detect attacks, and respond faster. The result is what he called a “supercharged” cybersecurity contest between attackers and defenders.

The article highlights manipulation as a major concern. AI could generate propaganda and radicalization material tailored to particular individuals. Personalized messages may make extremist ideas more persuasive and help hostile actors target people more efficiently. McCallum also raised the possibility that AI could help people make existing biological weapons, although the provided text ends before giving further detail.

These risks add a new layer to the threats already facing Britain. AI could strengthen state operations, criminal activity, and extremist recruitment while also improving defensive tools. The article presents rapid technological development alongside worsening security conditions, suggesting that governments will need to adapt quickly as capabilities change.