Despite the risk posed by militant groups like Islamic State, Boko Haram, Al-Qaeda and Al-Shabaab, cash-strapped governments across the region have chosen to either not increase their defense and counter-terrorism efforts as part of cost-cutting and austerity measures.  Last year, the European Union's Counter-Terrorism Coordinator, Gilles De Kerchove, warned the U.K. government's Home Affairs Select Committee on counter-terrorism capacity that national budgets devoted to counter-terrorism were declining across the EU but "that the threat that we face is becoming more diverse, more diffuse, and more unpredictable."  In addition, he called for "concerted and co-ordinated action" by European countries to "avoid destabilization … and the establishment of terrorist safe havens."  Read MoreConfusion as French hunt shooting suspects  Thursday's attack highlighted the importance of maintaining -- if not, increasing -- spending on counter-terrorism in Europe, another analyst told CNBC.  "Events like yesterday highlight the importance of counter-terrorism measures and intelligence gathering as being the core of security in societies within Europe," Alan Mendoza, executive director of London-based Henry Jackson Society think-tank.  "It's up to politicians to decide whether they think that's important enough to put the necessary resources in. We've seen defense cuts in this sort of area because of budgetary restraints and I think it's time to recognize that we need to up the ante on this," he added.  Mendoza said he could not put a figure on how much more needed to be spent on counter-terrorism measures but he believed that not enough investment was being made in intelligence gathering to prevent attacks.  "We have probably not invested enough in terms of our ability to intercept communications like this – it is controversial too as people don't like being snooped on but a balance needs to be struck between security and liberty."
With France reeling from several shootings in 24 hours, terrorism experts warn that budget cuts in Europe might hurt counter-terrorism efforts.