Petty Officer 2nd Class Joseph Castillo, hospital corpsman, from Combat Logistics Battalion Health Service Support Team, 31st Marine Expeditionary Unit, hands out medication during a medical civil action project at San Juan Elementary School. The 31st MEU is operating with the forward-deployed Essex Amphibious Ready Group as part of Balikatan 2010, an annual, bilateral exercise designed to improve interoperability between the U.S. and Republic of the Philippines.