It is a joint and combined training of military, civilian and police structures for participation in multinational peacekeeping operations under the mandate of the United Nations. NATO supported the activity providing assistance in an advisory role, with the involvement of the NATO HQ Joint Force Command Naples, as well as through funds for the participation of partner nations.

The training objectives, which were carried out in accordance with NATO standards and procedures, were focused on improving the capabilities of brigade-level staff officers to command and control forces in operations in a multinational environment, and on enhancing interoperability. After year-long comprehensive preparations, the Serbian Armed Forces (SAF) started the execution stage of command-staff exercises supported by computer simulations.

Since the establishment of the REGEX Initiative, this is the fifth in a series of exercises conducted by NATO since 2014. The SAF prepared the brigade-level command-staff exercise through seven training and planning workshops with foreign partners. REGEX is a multinational and multi-functional exercise whose concept supports the preparation and implementation of multinational peace support operations in an unstable environment, based on a comprehensive approach and focused on cooperation with all relevant actors in the area of operation. Apart from members of the SAF, members of the Special Anti-terrorist Unit of the Ministry of Interior, representatives of international organisations, UN Office in Belgrade, UNICEF, UNHCR, OSCE, International Committee of the Red Cross, Commissariat for Refugees, Red Cross of Serbia and around 60 members of armed forces from 15 other countries also took part in "REGEX 18”.