In June 1948, he began two years as deputy to the assistant chief of naval operations for guided missiles, Rear Admiral
Daniel V. Gallery. Over the next decade, he would build a reputation for missile expertise and eventually become known as the father of the Navy's guided-missile program.
Fleet ballistic missile Sides was promoted to rear admiral in 1952 as director of the guided-missile division in the office of the chief of naval operations. In that role, he directed the Navy's entire guided-missile program for almost four years, Sides handled the Navy's side of negotiations over how exactly to implement the Killian Committee's recommendations, which called for the Navy to develop a ship-launched FBM similar to the Army's
Jupiter IRBM. On September 13, 1955, President
Dwight D. Eisenhower accepted the Killian Committee recommendations and directed the Navy to design a sea-based support system for Jupiter. Sides and the Navy protested that liquid-fuel rockets like Jupiter were too dangerous for shipboard use and pushed instead for
submarine-launched solid-fuel rockets for tactical use against enemy submarine bases. However, on November 17, 1955,
Secretary of Defense Charles E. Wilson ordered the Navy to join the Army on Jupiter development, and specified that all such missile development would not be externally funded but would have to be carved out of the existing Navy budget. In October, following the unexpected Russian launch of the first satellite,
Sputnik 1, Sides spoke before the
American Rocket Society and
Institute of Aeronautical Sciences and disputed the Russian report of a successful ICBM test, claiming the reported August flight might actually have been an "errant sputnik" that failed to make its orbit. He was "certain that the enormous effort which went into the development and launching of Sputnik was at the expense" of the Soviet ICBM program, and asserted that "winning the race for development of long-range weapons systems is more important than getting up the first satellite."{{citation After the dramatic failure of the
first United States attempt to launch a satellite on December 6, 1957, Sides spoke at a conference of the
American Management Association on January 15, 1958, where he reiterated that the nation's development of long-range missiles was "progressing very well" and complained that a false impression had been created by missiles that failed in early tests. "It just so happened that about the time of the sputnik launchings, our intermediate and intercontinental ballistics missile flight-test programs were getting into high gear; and not being blessed with a Siberian proving ground, where we might do our testing in private, every malfunctioning test vehicle was given a play in all the media of public information. The impression was unwittingly created that we were really on our uppers, when, as a matter of fact, each one of these so-called unsuccessful missiles yielded a great deal of the very information it was fired to obtain. In ten years of missile experience I cannot recall a missile system in which similar casualties were not encountered in the early test flights. But in each case we have determined the causes, corrected the deficiencies and gone on to develop a successful weapon system."{{citation ==Commander in Chief, U.S. Pacific Fleet==