Brussels airport attack with explosives 'takes a while to plan' - international security expert
The Brussels attacks would have taken "quite a while" to plan as they involved explosives and targeting an airport, an international security expert has said.
Shashank Joshi, a senior research fellow at the Royal United Services Institute, urged caution in viewing the atrocities solely as revenge for the arrest of Paris plotter Salah Abdeslam.
He said: "This would take quite a while to plan, particularly involving an explosive, involving an airport. We should be wary of seeing it purely as a retaliation for Salah Abdeslam's arrest."
Terrorists risk the higher security at sites like airports in a bid to gain international attention, he said.
"It is higher security than a metro stop or a concert venue. It's an international site. It's almost a trade-off between dealing with higher security and the number of headlines."
Belgium's terror threat level was only raised to the maximum level in the wake of the explosions at Brussels airport and the metro system, but Mr Joshi said it is "far too premature" to blame the country's law and security forces.
"The maximum level can involve very costly, very burdensome measures which cannot be sustained for a long period of time. It's like an army mobilising. Intelligence agencies and law enforcement agencies face very difficult challenges. It's far too premature to blame them for their choices.
"Not all of these attacks are intelligence failures. It's an intelligence failure if it was something that was known and wasn't used, or dots weren't connected."
Terrorism expert Shiraz Maher said the attacks "underscore how pointed and significant the threat facing Europe is right now".
He believes that the attacks would have happened regardless of Abdeslam's arrest on Friday, and that a terror cell was "primed and ready to go".
"If it turns out to be Islamic State (Isis) it would not be retaliation for his arrest. Nobody could have put together a bomb and conceived an attack in three days. It shows the broader network that's sitting in some of these places that's already primed and ready to go."
Belgian authorities need to examine why it took so long to find the Paris attacker, he said.
"The real concern is that someone could hide out for a full month after the Paris attacks. It does demonstrate that the Belgian authorities need to become much better at detecting this kind of thing."
One explosion at Brussels airport was reportedly near an American Airlines check-in desk, and Mr Maher said jihadis leaving Syria are looking for "soft" targets symbolising US interests.
The senior research fellow at the International Centre for the Study of Radicalisation said: "Isis fighters coming out of Syria are not able to get to the US. It has become increasingly difficult. So they are looking to hit US symbols that are easier to get to.
"US embassies in any city around the world are heavily fortified, so they are looking for softer targets that they can use to send a message to the US. A check-in desk is an easy and unguarded soft target."