In February, Secretary of Defense Ashton B. Carter announced that the U.S. Navy would soon field a version of the SM-6 antiaircraft missile as a supersonic (Mach 3.5) antiship weapon. The SM-6 differs from earlier Standard Missiles in that it has an active (rather than semi-active) radar seeker; it is designed to attack enemy missiles beyond the horizon of the firing ship. It is already designed to maneuver violently at low altitudes to do so. What is interesting in the announcement is the way in which an existing proven missile can be quickly re-tasked. That is a consequence of the character of modern radars and control systems rather than of the specifics of the SM-6, and it is probably a harbinger of further conversions of existing weapons for new purposes.
World Naval Developments - Ever-Smarter Software = Ever-Greater Missile Versatility
By Norman Friedman