On the same day that Raqqa fell, the head of MI5, Andrew Parker, gave a set of interviews in which he said Britain faced the most severe terrorist threat that he has seen in over three decades working in the intelligence agencies. This contrast highlights the degree to which the risks facing the UK have transformed.

Instead of a terrifying but comprehensible campaign directed by surreptitious foreign networks, we are now facing a confusing and diffuse one whose link to terrorist organisations is ever looser. Daesh’s [the self-proclaimed Islamic State of Iraq and the Levant] loss of territory has not produced the surge in terrorist plots that was expected: in 2017 the UK faced five successful terrorist attacks, and yet, with the possible exception of the Manchester bombing, none have involved foreign fighters.

In some ways this lack of a sudden surge is not surprising. The notion of increased threat from foreign fighters after the collapse of the Caliphate was predicated on the idea that Daesh were somehow holding themselves back before — saving the potential strikes back home until they were at their weakest point. In reality, the group has been consistently inciting, directing and instigating terrorist plots in the West for the past three years.

What has changed, however, is the nature of the threat back home, where we continue to see individuals being mobilised by extreme ideologies but finding it harder to travel. Instead, a community of frustrated travellers is developing around the world, at a moment when the ideology and methodology of what constitutes a terrorist attack have become indistinguishable from random acts of violence. This helps explain the current picture. A threat abroad appears to be decreasing (through loss of territory, capability and manpower) just as a different sort of threat is expressing itself at home. But there is still an important question to be asked about what is going to happen to those individuals who went abroad to fight. Even according to Andrew Parker’s latest figures, at least a few hundred are still on the loose.

What these individuals do now will be determined in large part by their reasons for going to Syria in the first place. For some, the motivation to go and fight was ideologically pure and focused abroad. They were driven by a sense of injustice, religious duty or a desire to defend the Syrian people. For them, it is possible that the fight in Syria and Iraq is just the first stage in a long life of insurgencies abroad.

For others, the motivation was more selfish — seeking to flee a chequered past and gain redemption on the battlefield. Still others were drawn by friends, family, a sense of adventure or some other reason which now leaves them stranded in a conflict zone. Some may change sides to continue fighting in Syria; some will settle down in an ungoverned space; others will die, and yet more will move on to further zones of conflict. Few of them went out to come back home and be terrorists. In many ways it is the flow to Daesh’s affiliates elsewhere that should most concern us. These affiliates are already taking root in places like the Sinai, the Philippines, Libya, parts of Central or southeast Asia and Afghanistan. Those that can accept these battle-hardened warriors will welcome them, enhancing a range of problems that until now have appeared localised. Foreign governments aren’t always able to manage these problems and, in time, one of these groups may pick up the global organisation’s banner and become the new Daesh core.

The danger to us comes when these affiliates decide to launch attacks against the West, either in their immediate neighbourhood or further afield. The base in Libya has already produced a number of problems in Europe, and these may grow. But MI5’s attention is apparently on the domestic threat, which is increasingly unpredictable. Many recent terror plots have come from the loose cloud of individuals who are not primary subjects of interest. This community, which once seemed peripheral, is now becoming the main danger. Raqqa has now fallen. Daesh is not yet finished. But terrorism has already evolved into a new form that security services are struggling to manage. Foreign fighters will undoubtedly be part of the picture. For now, at least, they are not the core of the problem.

— The Telegraph Group Limited, London 2017

Raffaello Pantucci is director of international security studies at the Royal United Services Institute in Britain.