The world's first operational nuclear-powered ballistic missile submarine (SSBN) was with 16 Polaris A-1 missiles, which entered service in December 1959 and conducted the first SSBN deterrent patrol November 1960 – January 1961. "George Washington" also conducted the first successful submerged SLBM launch with a Polaris A-1 on 20 July 1960. Forty days later, the Soviet Union made its first successful underwater launch of a submarine ballistic missile in the White Sea, on 10 September 1960 from the same converted Project 611 (NATO reporting name Zulu-IV class) submarine that first launched the R-11FM. The Soviets were only a year behind the US with their first SSBN, the ill-fated K-19 of Project 658 (Hotel class), commissioned in November 1960. However, the Hotel class carried only three R-13 missiles (NATO reporting name SS-N-4) each and had to surface and raise the missile to launch. Submerged launch was not an operational capability for the Soviets until 1963, when the R-21 missile (SS-N-5) was first backfitted to Project 658 (Hotel class) and Project 629 (Golf class) submarines. The Soviet Union was able to beat the U.S. in launching and testing the first SLBM with a live nuclear warhead, an R-13 that detonated in the Novaya Zemlya Test Range in the Arctic Ocean, doing so on 20 October 1961, just ten days before the gigantic 50 Mt Tsar Bomba's detonation in the same general area. The United States eventually conducted a similar test in the Pacific Ocean on 6 May 1962, with a Polaris A-2 launched from as part of the nuclear test series Operation Dominic. The first Soviet SSBN with 16 missiles was the Project 667A (Yankee class), which first entered service in 1967 with 32 boats completed by 1974. By the time the first Yankee was commissioned the US had built 41 SSBNs, nicknamed the "41 for Freedom".