A show of strength. Firearms greeting football fans. These reinforcements rapidly drafted in. High alert after calls purportedly from the Islamic State Group to target Champions League matches. But here, threats to Paris and Germain against Barcelona, not troubling one high-profile guest, former France captain, Patrice Evere.

But I mean, are you sure to keep the world safe? Because I can ask that question. I don't think it's only about Paris. I think this world is unsafe.

But this week's threat did reference the terror attack on the Stade de France in 2015, adding to the alarm.

Arm police outside this Champions League game, and it will be a familiar sight throughout the summer as the city hosts the Olympics and the Paralympics, with the French authorities already strengthening security to try to keep spectators and athletes safe.

Anti-terror squads increasingly visible across France. The security alert raised to the maximum level. And extremism experts believe believe the IS are trying to remind of their capabilities.

The threat from IS is credible and serious. So it's a matter of not only when they will try to hit, but also where.

But these Parisians showing no fear.

How do you feel? Not afraid, actually. I truly trust in the security here. Does it seem scary with the Olympics and everything coming? It seems scary, but there's security for here, for us.

Enhance policing, providing reassurance rather than panic. Rob Harris, Sky News, Paris.