Spanish authorities said 16 people had been killed and scores more injured when a van drove through the popular tourist strip of Las Ramblas in Barcelona on Thursday in an attack immediately claimed by Islamic State.
Two men were arrested but the van driver was still at large.
Soon after, five terrorists, some wearing suicide vests, were also killed in a shoot-out with police in the coastal town of Cambrils, south of Barcelona.
Deakin University counter-terrorism expert Greg Barton said that while the investigation was in its early stages, the signs pointed to Islamic State's direct involvement.
“It does make a difference when it’s a networked attack,” Professor Barton told SBS World News.
“That was the case with the Madrid attacks back in 2004. As they chased down the network, they had a series of violent confrontations and that is a possibility they may be dealing with here.”
“With the London Bridge attack, it was just one man who had rented a car. Even with Manchester on the ground in the UK, it seems like just the one individual. It sadly looks as though Barcelona might be a bit larger, but all that is speculation until we get hold of the driver of the van.”
Terrorism in Spain
Unlike its neighbour France, which has been subject to a number of deadly incidents in recent years, the Barcelona and Cambrils incidents are the first jihadi terrorist attacks in Spain since the coordinated Madrid rail bombings in 2004 which left 192 dead.
Isaac Kfir, director of National Security and the head of Counter-Terrorism Policy at the Australian Strategic Policy Institute, said that was a credit to the work of the Spanish intelligence agencies and security authorities.
“They’ve managed to foil a number of attacks primarily through better cooperation with their counterparts in France and across the EU, and abroad,” he said.
“They used to have a problem with their prison population but they've also done a very good job with deradicalisation in Spanish prisons. That’s why it’s a little bit of a surprise to see this attack.
“In 2016 we do know the Spanish authorities managed to foil 10 terrorist plots. We don’t know if they were [all] Islamic State plots.”
Global insurgency
Some analysts have argued IS’s focus on executing terrorist plots in Western countries is a sign of their weakness as they have been forced into retreat from former strongholds in Iraq.
But Professor Barton cautions this may be an overly optimistic view.
“There is no question that they're going to have to try in their view to show proof of life, proof of potency, as they lose the physical caliphate. But the real uptick in attacks across Europe and across the Mediterranean world and the Middle East and Asia began in October 2015," he said.
“That's well before IS was on the back foot in the Middle East; that was when it was at the height of its power. It was always planning to have a global insurgency.
“And some analysts would argue they never intended to hold the physical caliphate indefinitely in Mosul and Raqqa - they understood that was not possible. But the physical caliphate was a launching pad for a global insurgency which was always the long term aim.
“That’s an even worse conclusion than to just say they’re under pressure and they’re acting out of desperation because of losses in the Middle East.
"Unfortunately I think any analysis that says they’re on the slide and this is a sign of weakness - there's some truth in that no doubt - but that’s probably also too much wishful thinking to be healthy."
Protecting pedestrians from vehicle attacks
Cities around the world have been grappling with a new awareness of the terrorism risk to pedestrians since the Bastille Day truck attack in Nice, France, in July 2016. Professor Barton said that the installation of traffic-slowing measures such as chicaines and bollards is a necessary measure in high foot-traffic tourist areas.
The other thing governments are doing, he said, is continually cultivating intelligence about radicalisation.
"That's not just picking up signals but also human intelligence, working with communities so that when somebody is concerned about a loved one or friend, they speak up. That’s saved us many times in the past.
"The prime minister's press conference this morning touched on that issue when he said that the Muslim community is our first and best line of defence. It’s not just nice rhetoric, it’s based in clinical intelligence assessments of how attacks have been thwarted."