UK facing ‘new era of national security’ with most foreign threats since Cold War, MI5 chief warns
The UK has entered a “new era of national security” with a level of threat from foreign states last seen during the Cold War, the head of MI5 has warned.
Speaking after his annual speech at MI5 headquarters in London, Sir Ken McCallum said the security service was directing more resources to keeping Britain safe now than in the Cold War, warning that essential services such as banking, flights, and healthcare were at risk of being disrupted by adversaries, including Iran and Russia.
And he warned about the growing threat of artificial intelligence provoking real fear that terrorists could use the technology for warfare, and that new bioweapons could be developed.
Putting the public on guard, Sir Ken warned: “We have again entered a new era of national security”.
He called for a “whole-of-society effort” to face threats to national infrastructure, warning that hacks could disable people’s banking services, drones could disrupt flights, and cyber-attacks on hospitals could impact health treatment.
The MI5 director general said that the suspected terror plot against RAF Fairford in Gloucestershire, which prime minister Andy Burnham said was “almost certainly” directed by Iran’s Islamic Revolutionary Guard, was “not unique in the UK”, with Iranians seeking to expand their hybrid campaign against Britain this year.
In the past twelve months, MI5 investigations have led to more than 50 arrests in Iran-linked operations in the UK, and its state threats caseload has quadrupled in the past decade, he said.
Sir Ken added: “You might be surprised to know that in 2026, MI5 is devoting more resource to countering state threats than during the Cold War.”
He said that there have been dozens of arrests under the National Security Act in the three years since it came into force, with cases linked to Russia, Iran and China.
“Anyone tempted by apparently easy cash from shady overseas taskmasters might want to bear this in mind,” Sir Ken warned.
He said that Russia remains “aggressor number one”, with Russian military and intelligence services “once again escalating their attempts at hybrid warfare” citing a cyber-attack on Polish energy infrastructure and an attempt to use a drone to blow up a cargo plane in Germany.
Sir Ken also called out Iranian use of “criminal proxies to try and intimidate oppositionists, Iranian media organisations and Israeli sites”.
Addressing journalists after his speech, Sir Ken said: “The Iranians in the UK are principally using a modus operandi of hiring criminals to do their biding. Their level of capability is really a function of the sophistication level of those criminals”. But he warned that the UK should be readying itself for more aggressive plots from the Iranian security services.
Speaking about the ongoing threats from terrorism, Sir Ken said that MI5 is still having to respond to attempts from radicalised Islamists to carry out mass casualty attacks in the UK. And an increase in extreme right-wing terrorism, with a growing number of cases where “extremist versions of anti-immigration and anti-Muslim grievance are tipping into terrorist intent”.
