The AGM-45 Shrike was the first dedicated air-to-surface ARM (Anti-Radiation Missile, sometimes also called Anti-Radar Missile) of the U.S. armed forces. It was used in very large numbers by the USAF and the U.S. Navy, until being replaced by the AGM-88 HARM. Development of the Shrike began at the NWC (Naval Weapons Center) in 1958 under the designation ASM-N-10. The missile was intended to counter the threat of the then new Soviet S-75 surface-to-air missile system (known to the NATO as SA-2 Guideline) by homing on the emissions of the SA-2's "Fan Song" guidance radar. The ASM-N-10 was based on the airframe of the AAM-N-6/AIM-7C Sparrow III missile, but had a larger warhead, smaller rocket motor, and smaller tail fins. In June 1963, the ASM-N-10 was redesignated as AGM-45A, and large-scale production of the initial AGM-45A-1 model for the USAF and the U.S. Navy began at Texas Instruments and Sperry Rand/Univac. It entered service with the Navy in 1965.