Under normal circumstances the last few minutes of Ireland's play-off in Bosnia could have been described as rather thrilling, as Robbie Brady burst forward under a cloak of invisibility to score a brilliant goal, and Edin Dzeko quickly equalised. But it was difficult to concentrate on what was happening out there in the Zenica fog.

What was happening in Paris had more immediacy. There had already been reports of an explosion at the Stade de France, where a capacity crowd was watching France play Germany. Initial reports indicated that the explosion or explosions had taken place at a bar near the stadium. Somehow, in the beginning, it was hard to process the idea that the crowd at the match was the target. But the next day, the Wall Street Journal reported that at least one of the three suicide bombers in Saint Denis had been intercepted by security as he tried to enter the stadium.

It seemed his plan had been to detonate his bomb amidst the crowd, creating a televised spectacular of horror and chaos.

Historic first

If the plan had succeeded, it would have been a historic first for Europe. There seems no more obvious target for a terrorist attack than a crowd at a big sporting event. But there are not many examples of it actually happening.

It’s tempting to conclude that a stadium where people have gathered to watch a sporting event is considered off limits even by the craziest of killers. That thought had occurred to me when covering the London Olympics three years ago. The media talk in the build-up had been dominated by grumbling about Zil lanes and so forth, but there were also worries about the possibility of terrorism. The threat had loomed over those Games since 2005, when London was confirmed as the Olympic host city and the very next day 52 people were killed in the 7/7 Tube bombings.

The week before the opening ceremony there were reports on the installation of anti-aircraft emplacements around the stadium in Stratford. At the entrance to every Olympic venue, there were airport-style security screenings carried out by uniformed troops.

The army had been called in because the private security firm G4S had proved unable to fulfil the terms of their contract. The soldiers were unfailingly polite, but the mere sight of armed and uniformed men tends to create a low-level anxiety, as your thoughts drift towards the question of why they have to be there in the first place.

The queues were long and the friskings were thorough and after the 20th security check you began to wonder whether this was really necessary. How real was this threat? Who could possibly gain by an attack on the Olympic Games?

It’s not easy to construe the Olympics as a symbol of imperialism or oppression. They stand instead for universal, positive ideals – youth, peace, internationalism. To attack the Games would be so obviously inhuman, so plainly an atrocity, that it was hard to imagine whose political agenda could possibly be advanced by doing it.

But this was a deeply complacent way of thinking, and not just because there had already been two terrorist attacks at previous Olympics. In 1972, 11 Israeli athletes and a German policeman were murdered by the Black September Organisation. In 1996, Eric Rudolph planted a pipe bomb in Atlanta's Olympic Park that killed a woman and injured 111 people, apparently as a protest against abortion.

Appalling as these attacks were, they could at least be fitted into certain familiar categories. The Black September terrorists specifically targeted Israeli athletes and announced political demands including the release of prisoners in Israel and Germany. The outrage conformed to a conventional kind of logic. Rudolph was a mentally unstable person, acting alone.

On Friday night, Paris was attacked by a group of people who methodically planned an operation designed to kill as many random people as possible, for reasons that are difficult to grasp with conventional reasoning. Their rationale is not made much clearer by the alleged IS statement claiming credit for the attack – a manic screed that revels in the deaths of “crusaders” and raves about prostitution and vice.

Gas chambers

As Germany’s central defender Mats Hummels posted on Twitter, “this world is fucked up right now.” There have always been war crimes and atrocities, but the perpetrators have usually made some effort to cover them up. The last thing the Nazis did before they fled the death camp at Auschwitz-Birkenau was blow up the gas chambers in an attempt to hide their true nature. The twisted metal and blasted masonry remains there to this day as a monument to denial.

Today people are filming themselves committing atrocities and putting the videos online for everyone to see. Rather than conceal their crimes they seek to publicise them. The rules appear to have changed. Anything is possible.

Tonight Ireland and Bosnia play for the right to go to the European Championships in France. Imagine the cloud of fear and intimidation under which this event will now be played out. We’re about to have the first football tournament in which a terrorist attack will not be just a vague dread at the outer margins of our consciousness. We’re going to be expecting it every day.