It was an attack designed not only to kill but to create panic and fear across Europe.
In targeting Brussels airport and a metro station close to European Union offices, brothers Khalid and Brahim el-Bakraoui and their accomplices did not care for the religion or nationality of their victims, only that they would probably be drawn from the international community.
And as the full horror of Tuesday’s attacks began to emerge, so too did another depressingly familiar feature of recent atrocities on European soil.
Those responsible for the slaughter of 31 innocent civilians and the maiming of scores more were themselves Belgian nationals, raised in Europe but inspired by the rancourous ideology of the group calling itself Islamic State.
In the hours that followed the twin bombings of Zaventem airport and Maelbeek metro station, security was being tightened across the UK.
While France and Belgium have so far been the front line in this latest wave of terror, the police and security services here are under no illusions about the risk that is being posed.
Like the attacks in Brussels, police believe the threat of a jihadist-style plot on the streets of Scotland comes from within and not from those seeking to enter the country from abroad.
But speaking to Scotland on Sunday, Assistant Chief Constable Ruaraidh Nicolson, who is responsible for counter-terrorism, said the nature of any attack was unlikely to be as “sophisticated” as those in Paris last year due to the relative difficulty of obtaining firearms. Asked about where the threat would come from, Nicolson said: “It’s going to be from people who are already in the country.
“That’s likely not to be the kind of firearms capability we’ve seen in Paris because we believe the profile of firearms in Scotland is much lower. It’s much more likely to be an unsophisticated attack.”
Police say community relations remain the key to defeating extremism, a battle they believe they are winning.
But in an indication of the difficulties they face, counter-terrorism officers were this week involved in a row centring on Glasgow Central Mosque after Imam Maulana Habib Ur Rehman described an extremist executed for committing murder in Pakistan as a “true Muslim”. The imam said his comments had been taken out of context.
While Police Scotland are most worried about homegrown extremists, they remain alert to the problem of young Scots heading to Syria for terrorism training – a route believed to have been taken by at least one of the Belgian attackers.
And although recent attacks in mainland Europe have involved well-organised terror cells, police are not discounting the threat of “lone wolf” plots such as the 2013 murder of Drummer Lee Rigby in south-east London.
While there is no intelligence to suggest anything imminent in Scotland, the threat level is at the second-highest level, meaning an attack is highly likely.
“We’re still taking cognizance of lone wolves, there’s no question about that,” Nicolson said.
“We’ve had Paris and Brussels, so it’s fairly important we take cognizance of that as well. It’s looking across the broad spectrum of what concerns us and making sure we have processes in place to make sure we don’t have these kind of attacks in Scotland. But also that, if we were to have intelligence that an attack was imminent, we are in a position to deal with that.”
Work has been continuing since the Paris attacks in November to assess the firearms situation in Scotland.
From the intelligence gathered so far, police believe the limited availability of guns makes the sort of roving assault seen in the French capital less likely.
But despite public avowals that Scotland has adequate numbers of armed officers, it is understood there are concerns among senior officers at the level of cover.
The Scottish Police Federation, a staff association representing rank and file officers, this week reiterated warnings it made in the wake of the November attacks in Paris that Scotland is “woefully under-equipped, under-resourced and under-prepared” to deal with a similar incident.
Calum Steele, the SPF’s general secretary, said: “Nothing’s changed in our view [since Paris]. The political language operates in ignorance of the policing reality and the intelligence/security reality.
“The government priorities seem not to reflect the fact that this new policing reality exists and that’s not just in Scotland but across Europe.”
The divisions that have occurred in some sections of Belgian society are something the authorities here are working hard to avoid.
“We know our communities are cohesive, but we’ve had the Glasgow airport attack and there’s no question from the work we’re doing that we have seen individuals who are of concern to us,” Nicolson said.
While conservative estimates put the number of Britons who have travelled to Syria at around 800, Police Scotland has repeatedly refused to confirm how many are Scots.
Only two cases have been documented, that of Aberdeen-raised Abdul Raqib Amin, who appeared in an IS recruitment film before being later killed, and former Glasgow schoolgirl Aqsa Mahmood, who quit university to travel to Syria and marry a jihadist.
“Communities themselves will prevent terrorism,” said Nicolson. “That’s going to be much more important than anything the police can do. To some extent, by the time the police are involved it’s too late.”
Despite police confidence in community relations, there has been criticism of some of the tactics employed to stop radicalisation, most notably the UK government’s Prevent strategy.
Richard Haley, chair of civil liberties group Scotland Against Criminalising Communities, said: “The police need to build genuine relations with the community, not relations that are driven by flawed theories about radicalisation. They shouldn’t be seeking to build links for that purpose, but to build links – because that is what good policing is about.
“There’s a danger the discourse around radicalisation is influencing the whole relationship between the police and the Muslim community.”