A group of U.S. Coast Guard, Navy and international mariners from all over the world listen to U.S. Coast Guard Cmdr. Tim Williamson as he gives a presentation on maritime interdiction and operations in Cartagena, Colombia for the annual UNITAS exercise Sept. 1, 2018. UNITAS is a series of high-tech surface, air and under-sea naval exercises designed to strengthen multinational cooperation and interoperability in support of the U.S. policy of engagement in South America. (Photo by Petty Officer 2nd Class Adam Stanton)