Our governing authorities in the security field are:

The European Union, which imposes general security rules representing the minimum level applicable at each European airport.
Each Member State may add to these general rules. The Belgian authority competent to add to the rules and verify their satisfactory application in Belgium is the Federal Department of Mobility and Transport.
In addition, Wallonia has created a further authority with a permanent presence at Brussels South Charleroi Airport through WPS (Wallonia Public Services).

For the sake of completeness, we note that the Police and Customs Services also have particular tasks at Charleroi Airport, although not related to security:

In the case of the Police, the main task is border control (Application of the Schengen Agreements) for departures, AND for arrivals for all NON-SCHENGEN origins.
In the case of the Customs , the main task is to control the import of certain goods into Belgium. This control only applies to arrivals.