CIMSEC – During the Cold War, NATO maintained anti-submarine competency and internalized lessons learned during the Second World War. The collapse of the Soviet Navy during the 1990s shifted the U.S. focus to power projection ashore in the Balkans and the Middle East, and anti-submarine warfare competencies across the joint force atrophied. As the era of near-peer competition began, the Navy looked at ways to recapture the hard-fought competencies and lessons lost since the end of the Cold War. In particular, the whole government approach to anti-submarine warfare (ASW) was reintroduced, known as “full-spectrum ASW.” The Navy is the domain owner for undersea warfare. As such, the Navy must be prepared to educate and explain undersea warfare doctrine and its roles to the rest of the joint force so that lessons written in blood are not repeated.