The DSI is tasked with neutralizing terrorist incidents and other violent public order disruptions for which regular police units are inadequately equipped.

[3] Since the regional Arrest Teams of the police were incorporated into the DSI in 2013, multiple units with an independent history have resided under a joint command.

Therefore, a distinction should be made between the respective histories of the Special Support Units (Bijzondere Bijstandseenheid, BBE) and the Arrest Teams (Arrestatieteams, AT's).

In 1973, the first Dutch counter-terrorist unit was established under the name Special Support Unit-Marines (Bijzondere Bijstandseenheid Mariniers, BBE-M).

The legislation included regulation which stated that the ATs could be deployed exclusively for the arrest of suspects known for illegal gun possession, while requiring permission of the public prosecutor as well.

Points of improvement became apparent after the problematic siege of a house in The Hague which was part of operations aimed at the arrest of terrorists belonging to the Hofstad Network.

Following a confidential experts report, the Second Balkenende cabinet decided to implement a revision of the Bijzondere Bijstandseenheid, the spearhead counter-terrorism unit at the time.

The DSI unofficially commenced operations in 2005, the formal establishment took place on 1 July 2006, and was at that time part of the National police services agency.

The government commission tasked with evaluating the effectiveness, however, found that the general consensus was that the service functioned in a good manner.

In addition to the execution of planned raids, ATs can respond to ad hoc cases such as terrorist incidents or disturbed persons.

The RRTs patrol the large cities and specific high-risk locations throughout the Netherlands on a 24/7 basis, and each consist of three AT operators in an armoured vehicle.

When operators are not working AT cases or RRT shifts, they are training their physical fitness, techniques and procedures and their respective team specialisation.

In addition to the planned raids the unit conducts, the AI maintains several strategically located operating bases for the Quick Reaction Force {QRF).

The QRF teams are on-call 24/7 and respond to actual instances of terrorist incidents or other violent cases that require an intervention.

[10] M-Squadron is the tip of the spear counterterrorist unit in the Netherlands and tasked with conducting large-scale, prolonged and complex interventions, such as ships, oil platforms, trains and airliners.

Moreover, the DSI can be easily distinguished from other specialised law enforcement tactical units while the grey gear also complicates police impersonation.

Lastly, the colour grey signifies the character of a mixed unit, situated between the 'blue' (law enforcement) and 'green' (military) worlds.

Each DSI operator is provided with a ballistic helmet, model Ulbrichts Zenturio, which is fitted with an armoured glass visor that can withstand multiple 9mm rounds.

In addition, all operators are provided with a lightweight Ops-Core FAST SF Super High Cut helmet that enables more freedom of movement and situational awareness.

Three AgustaWestland AW139 helicopters Dienst Luchtvaartpolitie are available for the Quick Reaction Air (QRA) to respond to incidents that require a larger presence of personnel.