Trident Juncture 2015 ( TRJE15 ) will take place from 28 September to 06 November in multiple locations across the Alliance including Italy , Portugal and Spain . Over 25,000 troops are expected to participate , with the purpose to train and test the NATO Response Force , a high readiness and technologically advanced force comprising of land , air , maritime and special forces units capable of being deployed quickly on operations wherever needed . The exercise represents the final step in the certification process for the command and control elements of the NATO Response Force ( NRF ) for 2016 where Joint Force Command ( JFC ) Brunssum will be the oncall Standby Command . The exercise will also allow Allies and partners the occasion to train , deploy and exercise in a complex and distributed environment .