Vought Regulus II

In June 1953 Vought received a contract to develop a supersonic successor to the SSM-N-8/RGM-6 Regulus cruise missile. The new missile was named Regulus II (although it was a completely new missile, and not a development of Regulus) and received the designation SSM-N-9. The SSM-N-9 designator had been previously assigned temporarily to the MGM-18 Lacrosse missile, before the latter was transferred to the Army as SSM-G-12.