JOINT BASE PEARL HARBOR-HICKAM (June 3, 2021) Sailors assigned to the Los Angeles-class fast-attack submarine USS Columbia (SSN 771) observe morning colors before departing Joint Base Pearl Harbor-Hickam for Exercise Agile Dagger 2021 (AD21). AD21 is a training exercise, with one-third of the Pacific Submarine Force getting underway, to assess warfighting readiness and build capacity for the joint force. (U.S. Navy photo by Chief Mass Communication Specialist Amanda R. Gray)