The guided missile destroyer USS Donald Cook (DDG 75) leads a five-ship formation conducting operations in support of Operation Iraqi Freedom. Destroyers and guided missile destroyers operate in support of carrier battle groups, surface action groups, amphibious groups and replenishment groups. Destroyers primarily perform anti-submarine warfare duty while guided missile destroyers are multi-mission [Anti-Air Warfare (AAW), Anti-Submarine Warfare (ASW), and Anti-Surface Warfare (ASUW)] surface combatants. The addition of the Mk-41 Vertical Launch System or Tomahawk Armored Box Launchers (ABLs) to many Spruance-class destroyers has greatly expanded the role of the destroyer in strike warfare.