Following the attacks against the United States on 11 September 2001, the OSCE recognized the need to establish a focal point in the Organization to co-ordinate and facilitate all its actions against terrorism. Within a short time, the Bucharest Plan of Action for Combating Terrorism, adopted at the OSCE Ministerial Council on 4 December 2001, provided the mandate for the establishment of the Action against Terrorism Unit (ATU).

The ATU supports the 57 OSCE participating States, the Chairman-in-Office and the Secretary General in their activities aimed at preventing and fighting terrorism. The overall objective of the Unit is to respond rapidly and efficiently, in co-ordination with internal and external partners, to requests from participating States for anti-terrorism assistance.