The metro is thought to be a prime target for terrorists. Guaranteeing security across the network is no easy matter as most metro stations have numerous entrances that all need to be guarded if they are to remain open.
A sizeable contingent of police officers and members of the Belgian armed forces will be deployed to guard the metro that will gradually be reopened to full capacity.
The rail stations Merode, Schuman, Delta and Brussels-West remain closed today Tuesday.
Belgian Justice minister Koen Geens, who at the weekend spoke of reopening the metro as early as Monday, conceded that he had been to quick to speak out: "It takes a while before all the officers from the federal police reserve and the members of the armed forces are operationally in place" he told the VRT.
It remains unclear how many soldiers will boost police numbers.