ADAZI MILITARY BASE, LATVIA - Five national flags blew in the breeze on a characteristic Latvian spring morning as soldiers representing their North Atlantic Treaty Organization nations assembled below.Col. Martins Liberts, land force commander, Latvian army, then strode before the mix of formations, commencing the closing ceremony of Summer Shield XIII, April 29, here.For the past two weeks, nearly 1,500 soldiers from Latvia, Canada, Germany, Lithuania and the U.S. conducted a diverse series of interoperability training exercises as the annual event marked its thirteenth year.Soldiers conducted sniper, combat boat, fast rope insertion extraction, missile and anti-tank training and a variety of other events during the first week, culminating into a five-nation field training exercise in week two."Summer Shield is a training exercise which is intended to train combat service and combat service support units," Liberts said. "It's deliberately made like that because normally they are in a supporting role for maneuver units. It's not always the best environment for them to train ... but this particular exercise was very focused on joint firing, engineering, chemical biological radiological nuclear (and) we exercised our medical capability (and) our logistic capability."Summer Shield's humble beginning as a mortar platoon training exercise multiplied over the years, becoming more complex each time."It's become larger and larger so this year it's multiple nations participating with different capabilities," Liberts added. "That only proves that we are on the right track. We are doing exactly what is needed, because if nations are coming and willing to participate with certain capabilities (and returning), that means they are gaining something off of this activity."Each country brought their own internal training objectives to the table, Liberts said. The objectives were then combined during the field training exercise to complete a common task."We were able to communicate on the same radio network, everybody," Liberts added. "We can conduct all fire missions, engineers, our scouts and snipers were able to communicate with each other. I can say this is the greatest level of interoperability so far in combat support, combat service support unit."Liberts said he feels this year's exercise was a success, benefitting each country involved.During the ceremony, Liberts presented commemorative plaques to participating units in thanks for their contribution and support.One or more soldiers chosen from each unit as the "best soldier" of Summer Shield XIII also received a plaque and gift from Liberts in recognition of their hard work.Once each unit was acknowledged, soldiers from the five nations lowered their country's flag as the Latvian national anthem played, signifying the conclusion of Summer Shield XIII.