U.S. Marines and participating multinational forces board a U.S. Navy landing craft, air cushion with Assault Craft Unit 4 during exercise UNITAS 2025 at Marine Corps Base Camp Lejeune, North Carolina, Sept. 25, 2025.UNITAS, which is Latin for “unity,” was conceived in 1959 and has taken place annually since first conducted in 1960. This year marks the 66th iteration of the world’s longest running annual multinational maritime exercise. The exercise trains forces in joint maritime operations that enhance tactical proficiency and increase interoperability with the presence of unmanned air, surface and submarine systems.