Europe has been the target of a series of deadly terror attacks in recent years, yet the nature of Thursday's attacks in Spain are "totally different", according to the managing director of a risk and security consultancy firm.
Spain launched a comprehensive counter terrorism operation on Friday after the country's deadliest terror attack in more than 13 years.
Police shot dead five would-be attackers on Friday after a suspected Islamist militant rammed a van into crowds in Barcelona, killing 14 people and wounding at least 100 others. So-called Islamic State has claimed responsibility for the incident though the claim has not yet been verified.
"It's totally different than Nice and Berlin because it is a much more sophisticated plot involving many more people which is extremely serious and extremely concerning," Olivier Guitta, managing director of GlobalStrat, told CNBC on Friday.