LONDON — British intelligence chiefs are considering putting the U.K. on high alert for a terrorist attack, as tensions rise around the world after the outbreak of war between Hamas and Israel.
According to people familiar with the matter, officials are weighing up whether to raise the government’s terrorism alert level to “critical,” the maximum state of vigilance.
The current level is set at “substantial,” which means an attack is “likely,” according to the government’s definitions. Raising it two levels to “critical” would mean that intelligence and security services regard an attack as “highly likely in the near future.”
No final decision has been taken, according to the people, who discussed sensitive security matters on condition of anonymity. The level could also remain the same or be raised one notch to “severe.”
Security officials across the West have been assessing the threat of violence inspired by the October 7 Hamas attacks in Israel, as well as by Israeli reprisals in Gaza. Europe has already seen two fatal attacks in recent days.
France raised its security level after an attacker last week fatally stabbed a teacher and seriously wounded two others. Earlier this week, two Swedish citizens were killed in Brussels in a terror attack; the suspect was subsequently shot dead by police.
The U.K.’s national threat level system is designed to give a broad indication of the likelihood of a terrorist attack, and is set by the government’s Joint Terrorism Analysis Centre and security service MI5.
The country’s threat level was last rated as “critical” in September 2017 following a bomb attack on the London underground. It has been at “substantial” since 2019.
When deciding whether to raise the threat level, officials sometimes have specific information about potential attacks, but consider a range of intelligence as well. They also look at likely targets, the scale of any potential plot, and whether an attack appears imminent.
Speaking this week before a summit of intelligence chiefs in California, MI5 chief Ken McCallum said there “clearly is the possibility that profound events in the Middle East will either generate more volume of U.K. threat, and/or change its shape in terms of what is being targeted.”
A higher terror threat level would prompt increased security activity such as more meticulous bag searches and checks at airports. The public would be asked to remain vigilant and report suspicious activity, but would not be expected to take any other action.
