A Ukrainian marine runs for cover while on an ambush mission during exercise Rapid Trident 2014 in Yavoriv, Ukraine, Sept. 23, 2014. Rapid Trident is an annual joint combined exercise involving the U.S. and Partnership for Peace member nations. Missions alternate in odd and even years. In odd years Rapid Trident is a field exercise, while in even years the exercise incorporates a command post exercise.