BRUSSELS -- The timing of Tuesday's attacks may have been forced by the pressure Belgian police were putting on the terrorists.
Last Friday, they raided a Brussels apartment and arrested one of the Paris conspirators. That raid also turned up the names of two brothers who went on to attack the airport and subway in Brussels.
An apartment in a quiet Brussels suburb may have been an important clue that came too late.
It was rented under a false name, according to Belgian media reports, by a man who turned out to be one of the suicide bombers -- Khalid El Bakraoui.
He and his brother Ibrahim -- who blew himself up at the airport -- were Belgian citizens with a history of violent crime. But they were not linked to terrorism until last week, when a police raid turned into a gun fight at the apartment.
One suspected terrorist was killed and two others escaped.
Inside the apartment, investigators said they found ammunition, an ISIS flag, and most importantly the fingerprints of Salah Abdeslam -- the alleged logistics man behind the Paris attacks.
That led to Abdeslam's capture three days later, but the apartment may have also linked him with the Bakraoui brothers.
The ammunition raised fears that another attack could be imminent.
But less than a week later -- before they were found or stopped -- the two brothers carried out their deadly plan.
On a laptop discovered by police yesterday, Ibrahim El Bakraoui wrote that he didn't know what to do, and feared he would end up in a prison cell.
Connecting the dots in a case like this one is not easy work -- and the Belgian intelligence agency has been criticized as understaffed and underfunded. Meanwhile though, Belgium -- by some counts -- has the highest per capita number of fighters in Syria of any country in Western Europe.