The United Kingdom is confronting a security threat more severe than that experienced during the 9/11 terror attacks, according to MI5 Director General Sir Ken McCallum. In a statement marking the 25th anniversary of 9/11, McCallum described the current threat landscape as "markedly different" from 2001, characterized by the resurgence of "dragons" – hostile states like Russia, China, and Iran – alongside the enduring threat of "snakes," referring to various terrorist groups.
McCallum issued a "call to arms," emphasizing that the UK faces unprecedented danger from these combined forces, which are increasingly leveraging advancements in artificial intelligence. He noted that while the ambition for mass-casualty terrorism persists, it now exists alongside strategic national security threats posed by capable states. These threats manifest as sabotage, covert interference in democracy, and destructive cyberattacks targeting critical infrastructure.
Reflecting on his personal experience during the 9/11 attacks, McCallum recalled being part of an MI5 team when news of the Twin Towers' destruction broke. At the time, counter-terrorism was a smaller division within MI5, but the events of 9/11 necessitated a radical transformation. The fight against al-Qaeda became the agency's top priority, leading to significant growth in investigative teams and a crucial shift towards intelligence sharing with domestic and international partners.
"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," McCallum stated. However, he stressed that past successes do not negate the need for continuous adaptation.
McCallum highlighted that in 2026, many critical assets and services under threat are privately held, meaning key decisions will often be made in corporate boardrooms rather than government crisis committees. He asserted that national security is no longer solely the domain of intelligence agencies but a "shared national endeavor" requiring cooperation across government, industry, and academia.
A Downing Street spokesperson confirmed the growing scale and complexity of threats from foreign powers and their proxies, which endanger lives and undermine democratic values. The government has expedited the National Security Act 2026 to grant new powers for designating state-backed organizations and proxy groups deemed a threat to national security.