A 'failure of intelligence' allowed the attacks in Brussels to happen, a Belgian security and terrorism has said.
A Brussels-based terrorism and security expert has told SBS News the attacks in the Belgian city were the result of a "failure of intelligence".
Speaking from Belgium, Thomas Renard, a terrorism expert at the Egmont Institute, a Brussels-based think-tank, said there had clearly been a "major failure" in the country's security services.
"To put it bluntly, when there is an attack, something went wrong and this is quite clear," he told SBS News.
"Now the question is, what went wrong, and we don’t know yet. Obviously at this stage it’s too early to tell."
He said the fault could be down to a multitude of factors including a breakdown in interagency communication and co-operation, security authorities underestimating the threat posed by people of interest or whether too much emphasis had been put into the hunt for the Paris attackers, including Salah Abdeslam.
A US government official told Reuters the attacks showed Belgium had not "upped their game" in national security, despite being home to more returned Syrian fighters than any other European country.
However Mr Renard said it was quite difficult to completely defend against attacks like that seen at the airport, where explosives were hidden in bags and under coats.
"How do you prevent this kind of people from walking into a metro station or walking in an airport hall way?" he said.
"Unless you live in a war zone where you have these kinds of security checks before entering the airport or before entering buildings - I don’t think that that in any of our democratic societies, citizens will accept these measures for more than one day.”
Since the attacks there have been harsh criticisms of the security at Brussels airport, but Mr Renard said these were "misplaced".
"If you go to Brussels, you’ll find exactly the same kind of preventive measures that you will encounter in any international airport," he said.
"Since last November when the threat level was raised to the highest level ... military personnel have been patrolling the airport on a daily basis.
"In Belgium we did not have military on the streets for a long, long time so it's just clear that this threat has been taken seriously.
"In absolute numbers, although not a lot of military personnel were actually in the airport, there were about 500 army personnel permanently in the street, now they’re raising that number to 750. It doesn’t seem much, but for a country like Belgium, it’s actually quite a lot."
However others are not so sure Belgium is on top of the security threat to the country.
The former head of the Belgian intelligence service, Alain Winants, told Reuters Belgium had been slow to adopt modern surveillance techniques and equipment, such as phone tapping.
He said police had even had to deny they let Abdeslam, who has since been arrested and is in custody in Bruges, slip through their fingers due to a law banning house raids at night.
Reuters reported the country had 193 local police forces, and in Brussels along there were 19 autonomous mayors - all part of a bureaucracy that hindered information sharing.
There were concerns not enough is being done to prevent disaffected young people from finding acceptance in the notorious Molenbeek area - a neighbourhood that has become synonymous with Islamic militants and radicalisation, Reuters reported.
Mr Renard said while some security measures had already been taken, there was “always room for improvement”.
"I think that the way to solve the problem is to increase the resources and the powers of our intelligence and security services on the one hand, and improve our prevention force and deradicalisation programs. I think these are the real priorities here," he said.
He said these attacks would most likely result in an investigation into how the attacks were able to be carried out.
"Not only will a lot of people raise questions about this, but I think they will criticise," Mr Renard said.
"In this case, there is certainly going to be an investigation on the investigation.
"First we will need to leave time and space for the police investigation, but once that is done, I am rather confident that there will be a parliamentary investigation or something similar and if they discover that there’s been a major issue related to lack of cooperation and coordination at the political level at the level or security of Belgium services, then in that case one may envisage a reform of their functioning."