In August 2014, a homeless, unemployed petty crook had his plan to behead a British soldier thwarted by the police. A recent convert to Islam from Jehovah’s Witnesses, Brusthom Ziamani appeared to be just another jihadi whose grand plans ultimately ended in failure—until, that is, he ended up in a British jail.

Operating among a sea of other radicals in HMP Woodhill, in Milton Keynes, a town 50 miles outside of London, Ziamani staked out a position of importance. According to an ex-prisoner speaking to the Times of London, Ziamani dubbed himself “chief of the Sharia police,” making the rounds in his block to ensure that no Muslim prisoners were breaking the fast during Ramadan.

Ziamani would bring wrongdoers to the makeshift sharia court he ran from the confines of a jail cell. The Times  describes how two “accused” appeared before Ziamani for the supposed crime of drinking alcohol. Ziamani decreed the punishment to be a beating, which two of his acolytes quickly—and savagely—delivered to the guilty parties.

This was not the only way in which the radicalism Ziamani had adopted outside of prison manifested itself once he was locked up. Ziamani would also approach newly detained Muslim prisoners about the depth of their faith, offering to take them to the “emir” of the prison, another convert, who would then deliver radical lectures from his prison cell.

Ziamani was eventually moved to another prison: HMP Whitemoor in Cambridgeshire. It was there, last Thursday, that he and an associate donned fake suicide belts, grabbed makeshift bladed weapons, and began to stab at prison staff while yelling “Allahu akbar.” Although there were no fatalities, five victims ended up in the hospital. British authorities are treating the incident as a terrorist attack.

The United Kingdom is not the only Western country to experience such attacks in its prisons. Al Qaeda’s first attack in New York actually did not occur on 9/11 but 10 months earlier in a Manhattan jail. Mamdouh Mahmud Salim, a founding member of al Qaeda awaiting trial in Manhattan on terrorism charges, sharpened a comb into an 8-inch blade and stabbed corrections officer Louis Pepe in the eye. The ordeal left Pepe physically and psychologically scarred.

This problem has also blighted France. In September 2016, a French Moroccan radical, Bilal Taghi, stabbed two guards in the radicalization assessment unit housing him in Val-d’Oise prison.

In January 2018, a former associate of Osama bin Laden’s struck in a different French prison: Vendin-le-Vieil in the country’s north. Christian Ganczarski, a German convert, attacked four guards with an edged weapon. French officials believe he carried out this attack in order to prolong his incarceration in France and prevent extradition to the United States, where he faces terrorism charges.

Then, in March 2019, Michaël Chiolo—who had become an extremist in jail—conspired with his visiting wife, Hanane Aboulhana, to stab two guards at Condé-sur-Sarthe prison in northwestern France. Chiolo was injured and Aboulhana killed during the police’s response. Chiolo said his actions were intended as revenge for French authorities killing Chérif Chekatt, the Islamic State-inspired jihadi who killed five and injured around a dozen more during a firearm and knife attack on the Strasbourg Christmas market in December 2018. (Chekatt himself had also been radicalized in prison.)

Clearly, there is an issue to be addressed. And while the U.K. is just the latest country to suffer the consequences, it had at least taken a preemptive approach to dealing with it.

In September 2015, the British government commissioned a report into Islamist extremism in prisons, probation, and the youth justice system. The report, carried out by Ian Acheson (a former prison officer himself), concluded that Islamist extremism was “a growing problem within prisons.” This extremism had manifested itself in a variety of ways, from so-called prison emirs who were “exerting a controlling and radicalising influence on the wider Muslim prison population” to “aggressive encouragement” of non-Muslims to convert to Islam to “Muslim gang culture and the consequent violence.”

In response to this gathering problem, Acheson recommended “a central, comprehensive and coordinated strategy … to monitor and counter” Islamist extremism in prisons. Acheson also suggested that radical Islamist prisoners be held together within specialist units, as opposed to being housed among the general prison population, in order to diminish their influence. On that front, the government correctly heeded his advice.

Yet there were other areas in which the government did not listen to him. Last month, Acheson lamented that the prison and probation services are “still not capable of managing a serious threat to our national security.” These claims were bolstered by last week’s events.

One area of concern involves prison chaplains. Most Muslim chaplains are Deobandis, a revivalist and highly conservative form of Islam. While this is not an indicator of extremism in and of itself, Deobandis are not representative of Britain’s Muslim population. Furthermore, the Acheson report concluded that the chaplaincy—while largely well intentioned—had “a weak understanding” of Islamist extremism. There had also been “a lack of management control over access to extremist literature and materials.” (This was likely a reference to a Times story from April 2016 that revealed extremist literature had been found in British prisons, including content justifying the murder of apostates.)

The extent to which chaplains are properly qualified, properly vetted, and actually have a positive influence on prisoners remains an issue of ongoing concern. The inability to recognize Islamist ideology when it presents itself is also a challenge. This is not just a problem limited to government: For example, after seeing the Times headline concerning Ziamani’s sharia trials taking place in prison, one staffer who focuses on countering violent extremism at a Norwegian NGO tweeted: “It is not strange if Muslims want to practice their religion in prisons. … Sometimes prison staff confuse religious practice with radicalisation.” Unfortunately, well-meaning NGOs sometimes confuse radicalization with religious practice.

In order to understand the Islamist mindset, the U.K. prison services should engage more with former extremists who understand the roots of the ideology but now champion British values and Western democracy.

Governments also need to adopt a more cautious when assessing the dangers posed by Islamist prisoners. Last November, Usman Khan, who had just been released from prison for previous terrorism offenses, stabbed two people to death and injured three others in London. Khan was regarded as a reformed character: The two people he killed worked for an organization that enabled students from universities and prisoners to study and learn together and that had used Khan as an example of a successful case study.

Khan was only free because his initial sentence of being jailed for an indeterminate length of time was quashed at the Court of Appeal and replaced with a more lenient one: 16 years, of which only eight years had been served. It is now obvious that this leniency was a mistake. Khan was clearly still a risk.

Similarly, in May 2016, appeals judges reduced Ziamani’s sentence from an initial 22 years down to 19 years due to his age. (He had just turned 19 years old when arrested.) He too, however, clearly posed an ongoing risk. A safety-first approach is required when it comes to such individuals.

The challenge is daunting. Prison services are attempting to diminish the prospect of those incarcerated getting exposed to extremist ideology. However, just as intelligence services cannot stop every terrorist plot, prison staff cannot detect every potential pernicious influence.

No approach is fail-safe. While accepting this reality, the U.K. government should assume that radical Islamist prisoners are ideological devotees, not vulnerable individuals who just happen to have been duped by extremist propaganda.

Naivety about their motives will only invite more problems for the U.K. government in the future. As Ziamani showed last week—and as many others demonstrated before him—the risk posed by radical Islamist prisoners does not come to an end just because they are behind bars.