MI5 chief warns Britain facing greater security threat now than at the time of 9/11 terror attacks

Britain is facing a greater threat to its security now than at the time of the 9/11 terror attacks, the head of MI5 has warned.Sir Ken McCallum issued a 'call to arms' on Friday, saying the UK is facing unprecedented danger from hostile states and Islamic extremism.The spymaster said he once hoped the demand for MI5's services would reduce after the end of the Cold War – a situation former CIA director James Woolsey characterised as the West having 'slain a large dragon' but facing a 'bewildering variety of poisonous snakes'.But now the MI5 Director General believes the national security threat has multiplied and intensified as the UK faces hostile state attacks from Russia, China and Iran, in addition to myriad terrorist groups who all seek to exploit technological advances in artificial intelligence.'We now face the worst of both worlds: dragons are back, but snakes persist,' he warned.Writing in The Independent to mark the 25th anniversary of 9/11, Sir Ken said: 'The MI5 I lead in 2026 contends with a threat landscape markedly different to 2001's.'Sadly, mass-casualty terrorist ambition endures... but the terrorist threat now sits alongside strategic national security threats posed by capable states.'Contending with rising state-backed aggression – whether sabotage subcontracted to criminals, or covert interference in our democracy, or destructive cyberattacks on power stations – demands new laws as well as new tradecraft.' Head of MI5 Sir Ken McCallum spoke at Thames House, the headquarters of the UK's Security Service in London in October 2025 A massive explosion in the south tower of the World Trade Centre after a hijacked plane crashed into the skyscraper. The events of 9/11 shook the world when hijackers took control of four passenger jetsIn a deeply personal account, Sir Ken revealed how he was working on an MI5 operational team countering terrorism when a colleague switched on a television after news of a plane hitting the Twin Towers.At the time, only a small number of spies worked in MI5's counter-terrorism investigative team and Osama bin Laden was named as the culprit within seconds.Sir Ken recalled that even as the second airliner struck, one of his colleagues said: 'Osama Bin Laden. I guess none of us leaves MI5 for at least a decade.'Although MI5 was immediately aware of the mastermind behind the attack, the effort to defeat al Qaeda would require a radical transformation in the way that Britain's spies worked, forcing them to share intelligence with domestic and international partners for the first time.In the aftermath of the attack, fighting terrorism became MI5's biggest priority, with investigation teams growing exponentially as Britain's Security Service was suddenly flooded by applications from recruits desperate to find those responsible.Sir Ken recalled: 'Al Qaeda had to be not just taken on, but taken down. A gargantuan multinational effort, powerfully spearheaded by the US, devised new capabilities to dismantle the core of the organisation. It worked. Al Qaeda remains a threat today, but its capabilities are a fraction of 2001's'.However, Sir Ken said MI5 could not rely on yesterday's tactics. 'The horrors of 9/11 will never leave me. What sits with me every day, 25 years on, is MI5's perpetual responsibility to keep adapting, at an even greater pace, as we seek to deepen the UK's resilience – now to both dragons and snakes,' he wrote.'The uncomfortable truth is that the next strategic shock may already be taking shape somewhere we are not yet looking.' Prime Minister Andy Burnham spoke via a video screen during the Commemoration of the 25th anniversary of 9/11 attacks at Queen Elizabeth Olympic Park in London on FridayThe spy chief added that Britain's national security will depend on co-operation across government, industry and academia to identify vulnerabilities.'In 2026, unlike 2001, many of the assets, systems and services under threat sit in private sector hands. This means many of the most critical decisions will be taken not in Cobra but in boardrooms,' he wrote.'This is my call to arms after 25 years: government, business, academia and the public must treat national security not as the specialist concern of a handful of agencies, but as a shared national endeavour.'A Downing Street spokesman said: 'The threat to the UK from foreign powers and their proxies has grown in scale and complexity, threatening lives and undermining our democratic values.'That is why we've fast-tracked the National Security Act 2026 to give the Home Secretary new proscription-like powers to designate state-backed organisations and proxy groups who threaten our national security.'READ MORE: Bombshell CIA 9/11 files lay bare Bill Clinton's horrific Bin Laden mistake...as ex-president grimly faces families at Ground Zero