These are the lessons Europe needs to learn after the Barcelona terrorist attack

In Northern Ireland there was for most of the Troubles what was once unfortunately but tellingly described by a British government minister as an 'acceptable level of violence', a sort of background noise of terrorism persisting for decades. We are facing a similar situation now

The aftermath of Wednesday's atrocity, which had echoes of attacks on Nice, Berlin, London, Stockholm and elsewhere (AFP/Getty)

It is not defeatist nor disrespectful to those who were killed in the terror attacks in Spain to state that more such atrocities are inevitable.

Inevitable, that is, because it takes so few resources and so little ingenuity or planning on the part of violent fanatics to cause such devastation to innocent, civilian lives.

As we have witnessed in so many places in Europe in recent times – Nice, Berlin, London, Stockholm and elsewhere – all that may be needed is a car or a lorry. Not much more sophistication is required to carry out a bombing such as that at the Manchester Arena. And while Western Europeans are shocked and appalled by this recent wave of terror, in great swathes of the world, especially in the Middle East, civilians have become wearily used to it.

Indeed in Northern Ireland there was for most of the Troubles what was once unfortunately but tellingly described by a British government minister as an “acceptable level of violence”, a sort of background noise of terrorism persisting for decades. It lasted then as it is lasting now in this new wave because the authorities, even with the most draconian measures or accurate intelligence, will never be enough entirely to eliminate terror. When matters descend into “tit for tat” killings across a cultural divide, then controlling the violence becomes even more difficult. While there have been some such low-level retaliations, Europe has so far been spared an escalation of this kind.

What next, then? Another review of security surrounding tourist and commercial centres in “global” cities is essential, and there can never be too much vigilance about protecting high-profile venues, sporting events, festivals, concerts and political or state ceremonies, for example.

Vulnerable thoroughfares need more obstacles to be placed in the way of a casual low-tech terror attack. There may be case, even, for more random security checks by the police and in private premises by security guards. Life, in other words, will become more irksome for many of us.

We will have to get used to it, tough, as we have with air travel, where the terrorists no longer favour targeting aircraft. The “ring of steel” of barriers and checkpoints that was thrown around the City of London during the IRA’s campaign against the financial centre in the 1990s is one such exercise that enjoyed success, though suicidal bombers obviously present a still more potent threat.

The more difficult issue to balance in countries where human rights and civil liberties are rightly cherished is what to do about those individuals “known” to the authorities as a potential threat, but are yet to commit any crime. The intelligence agencies, military and police already have sweeping powers and massively increased funding at their disposal. Still more, though, needs to be done if we are to avoid calls for the kind of internment without trial that does so much to alienate communities and, in fact, succeeds surprisingly little in combating terrorism (the truly determined jihadi finding detection and arrest easy to evade).

There may be a case to strengthen TPIMs (Terrorism Prevention and Investigation Measures) on certain individuals, or to bring back the tougher control orders which were abolished in 2011. These do erode but do not destroy civil rights in some cases, and the right balance between community safety and the freedoms that the nation is supposed to be defending in its struggle against terror has yet to be found. As with the more draconian calls for internment, though, the “professional” terrorists and their organisers – including those who have already served sentences – would not be greatly deterred. It would also be difficult to enforce.

Certainly the rabidly anti-Muslim keyboard warriors calling for revenge and worse on website comment sections might not wish for their activities to be placed under surveillance. Better, by far, would be to adapt and make more effective the Prevent strategy, flawed as some claim it is, to change hearts and minds, and, if true, to stem the flow of funds coming from Saudi Arabian or other sources that have been paying for extremist violent perversions of Islam to be spread. (And surely the time has come for Amber Rudd and the Home Office to publish their report into this).

Last, there is migration, or rather the lies and myths around it. The argument runs, as so often, that the migration crisis has created a crisis of security, though the geopolitical truth is that the cause and effect are precisely the other way round.

There are far too many home-grown terrorists, and victims of terror among refugees or economic migrants, for this to hold force. It is true that there will be some hardened jihadists and radicalised youths returning from Syria or Iraq, say, who may smuggle themselves into Europe, with our without a British passport, and with or without secreting themselves in rickety vessels trying to cross the Mediterranean. They will not be stopped by the navies of Europe returning every single migrant or refugee to North Africa, even if that were possible.

The truth about these modern terrorists is the same as it has been through the whole history of nationalist or political violence and sedition going back to the 19th century and way beyond: policing, security and intelligence are by far the best methods of protecting peace and the lives of our citizens. Where there is the possibility, peace or political process ought to be pursued, though with Islamists that is not a viable option now.

In any case, persecuting minorities has never worked and usually made matters far worse. That, indeed, is what the terrorists would like governments to do, because it simply foments more violence. We neglect that lesson at a very great, and continuing, cost.