Operation Christmas Drop is a tradition that started in 1951 that serves as a training mission for the U.S. Air Force. It has since become the longest-running U.S. Department of Defense mission in full operation, and the longest-running humanitarian airlift in the world. Supported by the local communities of Guam, it is primarily conducted from Andersen Air Force Base and Yokota Air Base, and targets Micronesia. The operation was first conducted in 1951,[3] when the aircrew of a WB-29 aircraft assigned to the 54th Weather Reconnaissance Squadron, formerly assigned to Andersen Air Force Base in Guam, was flying a mission to the south of Guam over the Micronesian atoll of Kapingamarangi. When they saw the islanders waving to them, the crew quickly gathered some items they had on the plane, placed them in a container with a parachute attached and dropped the cargo as they circled again.