U.S. Marines stand in front of the boat they used to help rescue a father and son on the Potomac River in Nanjemoy, Maryland, June 14. - U.S. Marines stand in front of the boat they used to help rescue a father and son on the Potomac River in Nanjemoy, Maryland, June 14.

U.S. Marine Pfc. Jacob Piazza, right, fires a .50-caliber machine gun at targets during realistic urban training aboard Camp Roberts, Calif., Dec. 14, 2014. Piazza is a rifleman with Weapons Company, Battalion Landing Team 3rd Battalion, 1st Marine Regiment, 15th Marine Expeditionary Unit. The training prepares the 15th MEU’s Marines for their upcoming deployment, enhancing their combat skills in environments similar to those they may find in future missions. - U.S. Marine Pfc. Jacob Piazza, right, fires a .50-caliber machine gun at targets during realistic urban training aboard Camp Roberts, Calif., Dec. 14, 2014. Piazza is a rifleman with Weapons Company, Battalion Landing Team 3rd Battalion, 1st Marine Regiment, 15th Marine Expeditionary Unit. The training prepares the 15th MEU’s Marines for their upcoming deployment, enhancing their combat skills in environments similar to those they may find in future missions.