Page "SSM-N-8 Regulus" Paragraph 12

Due to the high cost of the Regulus II ( approx one million dollars each ), budgetary pressure, and the emergence of the UGM-27 Polaris SLBM ( submarine launched ballistic missile ), the Regulus II program was canceled on 18 December 1958.

At the time of cancellation Vought had completed twenty Regulus II missiles with 27 more on the production line.

Production of Regulus I missiles continued until January 1959 with delivery of the 514th missile, and it was withdrawn from service in August 1964.