Airman 1st Class Nicholas Casillas, 96th Expeditionary Bomb Squadron crew chief, checks a U.S. Air Force B-52 Stratofortress engine before take-off at Royal Australian Air Force (RAAF) Base Darwin, Australia, Dec. 3, 2018. Two bombers along with aircrew and support personnel deployed to RAAF Darwin to enable the U.S. to train and increase interoperability with Australian counterparts in support of the U.S. Indo-Pacific Command's Enhanced Air Cooperation (EAC) program. The EAC comprises a range of air exercises and training activities designed to enhance regional cooperation, coordination and interoperability between Australian and U.S. service members. (U.S. Air Force photo by Senior Airman Christopher Quail)