PARIS — If another example of the failure of European intelligence services to share and act on information about potential terrorists was needed, Wednesday's identification of the bombers in the deadly Brussels attacks the day before certainly provides it.
At least one of the attackers, Ibrahim el-Bakraoui, had been deported by Turkey to the Netherlands last year with a clear indication that he was a jihadi.
"Despite our warnings that this person was a foreign terrorist fighter," President Recep Tayyip Erdogan of Turkey told a news conference in Ankara on Wednesday, "the Belgian authorities could not identify a link to terrorism."
By now it is abundantly clear that the terrorists who work for the Islamic State think, cooperate and operate across borders, ignoring national boundaries. The increasingly urgent question for Europe in its struggle against them is, Can it do the same?
The outlook is not promising. On Wednesday, there were renewed calls for a pan-European intelligence agency that would effectively share information from different countries. Members of the European Parliament took to the airwaves and print to denounce, again, the lack of coordination.
Yet the hurdles are as basic as national pride and bureaucratic turf protection, with experts pointing out that even within nations, intelligence-gathering agencies — France alone has some 33 of them — have trouble cooperating.
"Is it not in the nature of intelligence agencies to keep the information for themselves?" asked Jean-Marie Delarue, who until recently headed the French agency that reviews surveillance requests from these intelligence services.
"Information is power," Delarue said in a recent interview. "In intelligence, one only has enemies, no friends."
Cross-border cooperation would probably have helped prevent Tuesday's attacks. Erdogan said Wednesday that both the Netherlands and the Belgian authorities had been informed of el-Bakraoui's deportation, since he was a Belgian citizen.
What intelligence services in either country did with that information — and whether they shared it with one another or neighboring countries — was not immediately clear.
Yet it is certain that the absence of inter-European help was deeply harmful not only in Brussels but also in staving off the massacres in Paris last November.
The Paris plotters slipped easily in and out of Europe, then hatched their plans in one country, Belgium, before carrying them out in another, France. Then one slipped across the border again, taking advantage of the openness that is foundational to the European Union.
"We were victims of solidarity with the European Union," Delarue said of the Paris attacks.
"We think there should be cooperation," he added. "We rely on what the other countries give us. We are dependent on what they give us. And I don't think the Belgians gave us precise information."
A former top official with France's external intelligence agency, Alain Juillet, said the "big lesson" was to "restore the frontiers and establish better cooperation."
"There needs to be a permanent liaison with the Belgians," he added.
But if neighbors with a common language, a long common border, and common enemies cannot work together, who can?
Europe has had a "counterterrorism coordinator" for much of the last 10 years, but this fact-finding institution was dismissed as "weak" in a recent French parliamentary report and as "having no operational capacity to offer."
In the absence of an effective centralized European counterterrorism agency, it is up to the member states to cooperate with one another. Yet they do so only haphazardly.
There are plenty of databases, for instance, but the information they contain is either incomplete or inaccessible, numerous officials complained.
A fundamental one that contains criminal suspects' surveillance records — the Schengen Information System, or SIS — is only weakly supported by most of the member countries. The French parliamentary report last month said the French internal intelligence agency "is the only one that regularly feeds this database" and criticized "the very spotty nature of the information furnished by" other European nations.
"There is nothing automatic about what goes into the SIS," said François Heisbourg, a French intelligence expert. He said a decade of European squabbling over the issue had still not resulted in the creation of a minimal tool, the Passenger Name Record, of airplane travelers.
In addition, European Union rules forbid the use of the SIS system for spot-checks on individuals at Schengen's borders, according to the parliamentary report.
"On the one hand, there is a tension between the need to cooperate, which is recognized," said Thomas Renard, a terrorism expert at Belgium's Egmont Institute. "On the other hand, there is the lack of confidence that the different services have in each other."
"Everyone knows we need to work together," he added. "But for each specific case, they will say, 'We can't give up the information, because we are still working on the investigation.'"
It is not just the main SIS database that is woefully lacking.
Some 5,000 EU citizens are known to have traveled to Iraq and Syria to join the Islamic State and other groups. Yet the Europol database "contains only 2,786 verified foreign terrorist fighters entered by EU member states," the counterterrorism coordinator pointed out in a recent report.
"I think the biggest problem lies in the different levels of professionalism among the security services in Europe," Guido Steinberg, of the German Institute for International and Security Affairs, told German public broadcaster ARD on Wednesday.
"We have an enormous number of well-equipped states such as France and Great Britain, to those who are weaker such as Germany, to those who are completely overwhelmed such as Belgium," Steinberg said.
Another European database contains 90,000 fingerprints, "but there is no search possibility yet," the counterterrorism coordinator pointed out.
"We must have a permanent exchange on the European level," Elmar Brok, a European Parliament member close to Chancellor Angela Merkel of Germany, told ARD on Wednesday.
The February French parliamentary report ruefully acknowledged, without citing a specific assault, systematic "gaps in the transmission of information, which, if they had been realized in time, could have forestalled the attack" in Paris.
The cross-border cooperation failures in the case of the November Paris attacks are a telling case study.
Ex-intelligence officials here said that the Belgians were apparently unaware that the presumed ringmaster of the attacks, Abdelhamid Abaaoud, one of the most wanted terrorists in Europe, was on their soil before the attacks.
Abaaoud had indeed boasted, both in the Islamic State magazine and to a cousin, Hasna Aitboulahcen, about how easy it was for him to slip in and out of Europe.
"These were people who crossed frontiers, and they weren't even seen," said Juillet, the ex-official in the French foreign intelligence agency.
Bernard Squarcini, ex-head of French internal intelligence, asked, "What did the foreign intelligence service give us, what did the Belgian agencies give us?"
"Either we get organized, or we get eaten up," Squarcini said.