U.S. Marine mortar men with Weapons Company, Black Sea Rotational Force, fire an M252 81 mm medium-weight mortar system as part of a live-fire training during Exercise Summer Shield at Adazi Military Base, Latvia, March 29, 2015. Service members from Latvia, Lithuania, Luxembourg, Germany, Canada, and the United States participated in the exercise March 22-31 to demonstrate their capability to employ a NATO response force in the region.