But while pleased with the performance of Belgium's hitherto much criticized security services, Prime Minister Charles Michel warned that further threats to Europe were still live: "We are positive about the recent developments in the investigation," he told a news conference. "But we know we have to stay alert."
Mohamed Abrini, believed to have helped prepare the Nov. 13 Paris attacks, was seized on a Brussels street on Friday. Prosecutors said he confessed to being the "man in the hat" seen at the city's airport with two suicide bombers on March 22. That further confirmed close links between the two operations.
In a statement, prosecutors also said they had confirmed that a second fugitive seized separately on Friday in Brussels was indeed the man seen with a third suicide bomber on March 22 who struck shortly afterward on the Belgian's capital's metro.
Identified by officials as Osama K. and widely named in local media as a 28-year-old Swede called Osama Krayem, this man was also filmed buying bags used to carry the Brussels bombs and his fingerprints were found, like Abrini's, in an apartment used as a bomb factory and safe house for the Brussels attackers.
Also like Abrini, Krayem was identified as associating with the prime surviving Paris suspect Salah Abdeslam in the days and weeks before the November bloodbath that left 130 people dead.
As with other suspects in both Paris and Brussels attacks, police believe Krayem returned from fighting with Islamic State in Syria via refugee boats last summer reaching Greek islands.
The arrests have crowned a month of success and dramatic failure for Belgian security services, which have been under huge pressure at home and abroad since it became clear that the Paris attacks were organized from Brussels by local men, mostly known to police, who appear to have orders and funds from Syria.
On March 15, a raid on a house in Brussels left one wanted militant dead and put police on the trail of Abdeslam, who, with Abrini, rented accommodation for the Paris attackers and whose brother had blown himself up at a cafe on Nov. 13. Police moved on March 18 to arrest Abdeslam and another wanted Paris suspect.
That may have precipitated the attacks, now blamed on Abrini and Krayem, in which two suicide bombers struck Brussels airport and another the city's metro, killing a total of 32 people. All three bombers were being hunted for links to the Paris attacks.
The rolling up of wanted lists, however, has not reassured many European security services. Many such arrests have led to others, previously not sought, being detained and often charged.
Of two other men taken in and charged with terrorism offences following the arrests of Abrini and Krayem, one, Bilal El Makhoukhi, had until last month been serving out under electronic monitoring a five-year sentence for recruiting fighters for Syria.
Convicted early last year in the trial of dozens of members of an organization known as Sharia4Belgium, Makhoukhi, who lost a leg fighting in Syria himself, had been freed only last month, Justice Minister Koen Geens told reporters.
Abrini was tracked down the day after police released new images of "the man in the hat" pushing a laden baggage trolley similar to those of the two suicide bombers alongside him.
Of his confession, a spokesman said: "He had no choice."
Abrini, 31, was well known to police as a petty criminal and drug dealer who was a regular at the bar run by the Abdeslam brothers in the Molenbeek district of Brussels which is home to many other Moroccan immigrant families. Prosecutors said he told them that he had sold the hat he used to conceal his features.