Royal Navy Type 23 Duke-Class Frigate HMS Argyll (F231) and Spanish Navy Alvaro de Bazan (F100) class Guided Missile Frigate Cristobol Colon (F-105) participate in exercise At Sea Demo/ Formidable Shield May 18, 2021. At-Sea Demo/Formidable Shield, conducted by Naval Striking and Support Forces NATO on behalf of U.S. Sixth Fleet, is a live-fire integrated air and missile defense (IAMD) exercise that improves Allied interoperability using NATO command and control reporting structures. (Royal Norwegian Navy photo by Magnus J. Horne)