Russian military observers scan the horizon during the rehearsal of Trident Juncture 15 military exercises in San Gregorio training area, Spain. Under Vienna Document 2011 rules, observers from Germany, Russia, Sweden, Switzerland and the United States are in Spain 1-4 Nov., 2015, as this is where the largest concentrations of troops are during Trident Juncture 15. This program of military activities was coordinated with Spain and NATO’s Conventional Arms Control Coordination Cell. (NATO photo by Edouard Bocquet)