The starboard side Mark 15 Phalanx close-in weapons system aboard the guided missile cruiser USS Vicksburg (CG 69) fires 20 mm rounds during a calibration live-fire exercise in the Atlantic Ocean Sept. 24, 2014, during exercise Joint Warrior 14-2. Joint Warrior is a United Kingdom-led exercise designed to improve interoperability between allied navies and prepare participating crews to conduct combined operations while deployed.