The alleged failure of Belgian authorities to foil deadly attacks on the airport and metro this week has fuelled new questions about the nation's ability to handle the extremist threat.
The Belgian authorities have specifically come under fire for allegedly failing to take heed of security advice it had sought from Israel.
The criticism comes after it emerged on Friday that the Belgian government some weeks ago hired an Israeli security firm to inspect security arrangements at Brussels Airport.
DEBKAfile, an Israeli company, were asked for advice on improvements and submitted initial recommendations for urgent upgrades.
However, those improvements had not been installed by March 22, when the terrorists struck. The Israeli firm was apparently not alone in underlining the urgency of security upgrades at Zaventem airport in recent weeks.
On 29 February, EU security agencies called for an immediate overhaul of the security measures at Belgian airports and borders, which were "wide open" to access by terrorists and lacked the tools for inspecting passengers on arrival and departure.
These include Brussels' second airport in Charleroi, the terminus for charter flights to and from Algeria, Tunisia and Turkey.
Although the Belgian authorities were warned that Charleroi presented Isil terrorists with an open door from those countries into Europe, passengers passing through were still not subjected to searches.
Thirty one people died in the attacks on Tuesday and scores of others were injured.
Demir Murat Seyrek, a Senior Policy Advisor at the Brussels-based European Foundation for Democracy said, "There is certainly an intelligence failure and Belgian authorities have already recognised this issue. Lack of mechanisms and structures to share intelligence is the main problem. However, this is beyond Brussels and Belgium."
"We need better coordination and cooperation between intelligence services in the EU and this should include our close allies like Turkey and the US."
"Moreover, there's a fundamental issue specific to the EU. There are open borders and free movement is one of the fundamental principles of the EU."
"However, our security and intelligence services are not designed in line with this reality. Coordination and cooperation are at minimum level and they still work as they would do in a traditional nation state structure. That's why we need to address this issue urgently. We need mechanisms and structures to share intelligence across the EU and beyond."
Further comment came from Boaz Ganor, founder and Executive Director of the renowned Institute for Counter-Terrorism in Herzliya, Israel, who said that, "the Belgian security services in particular and the Europeans in general must carry out thorough self-examination to discover how an attack of this scale went unnoticed beneath their radar."
"Belgium must develop better intelligence capabilities alongside a more effective doctrine to cope with terrorism."
However, European Commission President Jean-Claude Juncker defended Belgian efforts to combat extremism, saying, "People should stop lecturing Belgium."
He added, "If, as President of the Commission, I were to address offensive comments against every country in the periphery of Europe that deviates from normalcy, I would be busy doing that day and night. I would never stop."
"I think people should be careful about the sort of things they say. People should refrain from making excessive statements."
"With respect to the Kingdom of Belgium, there were statements that were going too far, which I reject with all my forces, because Belgium is an honourable country and a great nation".
Meanwhile, the manhunt for those involved in the attacks continued on Friday with the Belgian public broadcaster RTBF reporting that Belgian police had launched a series of raids across Brussels overnight, detaining six people including three in a vehicle outside the prosecutor's office. Two people were taken into custody in Brussels' Jette neighbourhood and one was detained in a different part of the city.
On Friday morning, police conducted another raid in the city's Forest commune leading to more arrests although the Belgian federal prosecutor's office did not say how many people were detained.
The Belgian media also reported that the third bomber - the man in the white coat who was captured on CCTV cameras at Brussels Airport shortly before the suicide attack - is Abrini Mohamed, aged 30 and said to be one of the accomplices of Paris attack suspect Salah Abdeslam.
Sudpresse newspaper quoted an unnamed Belgian security official saying that the reports were "credible because the cell that prepared the attacks of Paris also participated in the implementation of the Brussels attacks."
Belgian newspapers also reported that while not mentioning the name of Abrini, the US authorities know the identity of the "man in white" and that he appears on the US terrorism watch list.
Investigators released a photo showing three men pushing carts with black bags in the hall of the airport moments before the explosion.
The identities of two of the individuals are known: one is Ibrahim El Bakraoui in the middle and Najim Laachraoui to the left of the image. The only one still unknown is to the right of the photo. He fled - perhaps with the help of accomplices - after leaving a bag that contained the largest explosive charge.
Elsewhere, leaders of four mainstream European political parties signed a declaration condemning the attack.
They include PES President Sergei Stanishev, who said: "The attacks in Brussels were against our free and open societies and against our peaceful coexistence. That's why the PES came up with the idea for this declaration, because there should be no differences between different parties when we have to defend the values of human rights and democracy. I am glad that all major European parties signed the document."