On the 25th anniversary of 9/11 terrorist attacks, Ken McCallum, the head of MI5 in the UK, issued a warning that intelligence and security agencies around the world should not become too engrossed in past threat models, but rather should prepare to address new types of “strategic shocks” different from the events of 9/11. He further cautioned that the next major impact might already be forming in areas that security agencies have yet to focus on.
McCallum, in a commentary article published on Friday by The Independent in the UK, emphasized the need for intelligence agencies to learn from past events like 9/11 but not to combat “yesterday’s enemies” or target “yesterday’s objectives” with “yesterday’s methods”.
He noted that the next “strategic shock” by definition would not be the same as the previous one and expressed concern that the next significant impact “may already be gradually forming in some place we have not yet paid attention to”.
The 9/11 attacks occurred on September 11, 2001, when al-Qaeda hijacked four commercial airplanes, two of which crashed into the twin towers of the World Trade Center in New York, another into the Pentagon near Washington, D.C., while the fourth crashed in Pennsylvania. This terrorist attack resulted in nearly 3,000 deaths and dramatically altered global counter-terrorism and security policies.
McCallum mentioned that although al-Qaeda has been weakened, the organization and other armed groups still harbor intentions for large-scale attacks leading to casualties.
He cited a foiled Islamist terrorist plot in the Manchester area in northern England as an example. The plot involved plans for a large-scale shooting targeting the local Jewish community, demonstrating that the threat of mass terror attacks has not disappeared.
The two individuals involved in this conspiracy were arrested in 2024, convicted in December 2025 for preparing acts of terrorism, and sentenced in February 2026 to life imprisonment, with minimum terms of 37 and 26 years. Authorities revealed that the main perpetrators had acquired firearms and a substantial amount of ammunition, conducted reconnaissance, and attempted to carry out a large-scale attack on the Jewish community before undercover operatives thwarted the plan.
Apart from terrorism, McCallum also warned that MI5 is facing an increasing level of state-sponsored adversarial activities.
He highlighted threats including sabotage actions carried out by criminal agents and cyberattacks targeting critical infrastructure such as power stations. This signifies that the current security environment in the UK is no longer solely threatened by traditional terrorist organizations.
In recent years, MI5 has openly warned that the UK is contending with espionage, cyberattacks, sabotage, and other adversarial activities orchestrated by state actors and their proxies. In July 2026, MI5 stated that the UK is under threat from state actors attempting to harm the country through arson, sabotage, and violent attacks on the public and businesses.
McCallum stressed the need for governmental, corporate, and academic collaboration to identify and mend security vulnerabilities within critical systems and services held by the private sector. He warned against waiting until after the next significant impact to question responsibility for vulnerabilities, the authority to take action, and who should have picked up the phone.
He urged society not only to remember and mourn the victims of the 9/11 attacks but also to prepare for the next significant impact, enhance societal resilience, and have the courage to adapt responses according to evolving threats.
Finally, McCallum concluded with the analogy of the post-Cold War security environment as a situation involving both “dragons and snakes,” emphasizing that the world is currently facing multiple threats from both state and non-state actors.
This analogy was derived from former CIA director James Woolsey, who in 1993 mentioned that although the West had “killed a dragon,” referring to the defeat of the Soviet Union, it had entered a jungle full of various “snakes.” Australian strategic expert David Kilcullen further analyzed state and non-state security threats using the “dragons and snakes” metaphor.
McCallum concluded by stating, “The terror of the 9/11 attacks will never be erased from my heart. It has lingered in my mind for 25 years, and now MI5 is always burdened with the responsibility of adapting to change, and at a faster pace. Because now we must combat both dragons and snakes.”
He emphasized that security agencies cannot focus solely on familiar threats but must also address adversarial actions originating from various sources, of different scales, and in different forms. For MI5, this means that counter-terrorism efforts must remain vigilant while also accelerating responses to state-sponsored threats and security challenges posed by emerging technologies.