The terrorist attack in Strasbourg, France, on Tuesday, doesn't look too bad on paper. Two people were killed, one victim severely brain-injured, and six seriously wounded. But the attack is more serious than it appears.

First off, the suspect, Cherif Chekatt had access to a semi-automatic weapon. According to Le Monde, grenades were also found in Chekatt's apartment. Finding out how Chekatt accessed these weapons will be a top priority for authorities. While firearms are far easier to access in France than in Britain, for example, it should not have been easy for someone on terrorist watchlists, like Chekatt, to access the type of weapons he did.

It's also relevant that the Islamic State, has a particular penchant for segregating weapon supply networks from its operational cells and inspired followers. Though it is on balance unlikely with what we know so far, a broader network cannot be ruled out here. Certainly ISIS is more skilled at infiltration than many assume: a suspected ISIS cell was broken up in France as recently as September 2017. Indeed, a number of European-focused ISIS attacks have been prevented by the U.S. and U.K. intelligence communities over the past two years.

Next up is the issue of Chekatt being radicalized towards Islamic extremism while serving a non-terrorism-related prison sentence. In-prison radicalization towards Salafi-extremism (the ideological base of ISIS and al Qaeda) is a major challenge in Belgium, France, and Germany in particular. But if Chekatt was radicalized and then deployed into action, it obviously raises the prospect others in his network of prison friends have also been. French and German authorities will urgently seek to trace individuals that Chekatt was incarcerated alongside.

Finally, there's ISIS' longstanding interest in attacking Christmas markets and similar events in European towns, not simply in major European cities. Reflecting this concern, as well as the fact that Chekatt remains at large, French authorities have upped their alert level and are boosting their security presence at Christmas themed events across the nation. That said, it is a positive sign that Chekatt didn't blow himself up after being confronted by police. That suggests that even if he is linked to other individuals, those individuals probably lack an explosives support network.

Regardless, this incident ultimately reminds us that even as ISIS's territory in Syria shrinks, its ideological influence will remain strong.