Unaware by the American public the much-publicized 1960s era space race was as much about developing ballistic missiles as it was putting a man on the moon. And more specifically achieving submarine launched ballistic missile (SLBM) capability because there was an equally crucial and secret undersea duel being waged between the United States and the Soviet Union, the victor of which would seize a strategic advantage in the control of the world’s oceans. So, in addition to appealing to national pride and patriotism the space race was permitted by the U.S. government to be so “in your face” public in order to exploit it as a cover for the unseen drama being played out beneath the seas. It was so vital to be first that when the USN had perfected the Polaris missile in 1968 but hadn’t a launch platform completed yet that in order to rush an FMB submarine into sea service it repurposed the USS Scorpion SSN-589 Attack boat still under construction at the Electric Boat shipyard by cutting it in half to insert a missile compartment and then rechristened and commissioned it the USS George Washington SSBN 598. Subsequently, soon after the Soviets succeeded in developing their own SLBMs and a launch platform then the nuclear arms race was underway in earnest.
The USN’s initial attempt to develop an SLBM was the SSM-N-8A Regulus/Regulus-I, a ship-and-submarine-launched nuclear-capable turbojet-powered second generation cruise missile deployed from 1955 to 1964 that delivered a 3,000 pound warhead at a range of 500 nautical miles at Mach 0.85/647 MPH speed. Regulus was initially guided toward its target by submarines or surface ships or it could be flown remotely by chase aircraft. However, later on, utilizing the TROUNCE system of Tactical Radar Omnidirectional Underwater Navigational Control Equipment, a single submarine could guide it.
Regulus’ first launch from a submarine was in July 1953 from the deck of the modified WWII fleet boat USS Tunny SS-282 initiating Tunny and her sister boat USS Barbero SS-317 as the United States’ first nuclear deterrent patrol submarines. They were joined in 1958 by two purpose-built Regulus submarines, USS Grayback SS-208 and USS Growler SSG-577, currently a museum boat at the Intrepid Sea, Air, and Space museum NYC; and later the nuclear-powered USS Halibut SSGN-587 which having a large internal hangar could carry five missiles and was intended to be the prototype of a future class of cruise missile firing SSG-N submarines. Operating from Pearl Harbor Hawaii the five submarines completed 40 nuclear deterrent patrols between October 1959 and July 1964 including during the Cuban Missile Crisis of 1962. And in the event of a “hot war” their primary mission would have been to eliminate the Soviet naval base at Petropavlovsk-Kamchatsky near Vladivostok Russia. Those deterrent patrols were the first ever in the history of any submarine Navy. However, the Regulus missile system had significant operational weaknesses in that pre-launch it dictated the submarine be surfaced for its active radar guidance of the missile to the target while inadvertently broadcasting its location. And because the missile was subsonic the launch platform remained vulnerable to attack during its lengthy flight duration risking destruction by the enemy and that would effectively abort the missile in flight. Regardless, the Regulus program was significant because it provided the first nuclear strategic deterrence force for the USN during the early years of the Cold War, it heralded in the Polaris, Poseidon, and Trident missiles that followed, and it was also the harbinger of the Tomahawk cruise missile.
Previously the original practical design of a submarine-based missile launch platform had been developed by the Germans during WWII applying a V-2 ballistic missile variant that was towed behind a submarine designated with the code-name Prüfstand XII. However, the war ended prior to it being tested and later its German design engineers were enlisted by the United States and the Soviet Union to develop their SLBM programs. Subsequently, a converted Soviet Project 611 Zulu-IV class diesel electric submarine test launched the world's first SLBM the R-11FM, a variant of the SS-1 Scud on 16 September 1955 then five additional Project V611 and AV611 Zulu-V class submarines became the world's first operational “Ballistic” missile firing submarines. Nonetheless, the world's first operational “nuclear-powered” ballistic missile submarine (SSBN) was the USS George Washington SSBN-598 with 16 Polaris A-1 missiles that had a range of 1,400 nautical miles carrying a single W-47-Y1 600 kt nuclear warhead and having an inertial guidance system with thrust vectoring that provided a target error probability of 5,900 feet. George Washington entered service in December 1959 and conducted the first SSBN deterrent patrol November 1960 to January 1961. Prior it had conducted the first successful submerged SLBM launch with a Polaris missile on 20 July 1960. Then forty days later on 10 September 1960 the Soviet Union succeeded in its first underwater launch of a submarine ballistic missile in the White Sea putting the Soviets close behind the U.S. with their first SSBN, the ill-fated Project 658 Hotel Class K-19 commissioned in November 1960 that carried only three missiles and had to surface to elevate the missile for launch, so the submerged launch was not an operational capability for the Soviets until 1963 when their R-21, missile was first back fitted to Project 658 Hotel class and Project 629 Golf class submarines.
Subsequently the Soviet’s surpassed the U.S. in launching and testing the first SLBM the R-13 SS-N-4 having a live nuclear warhead in the Arctic Ocean at the Novaya Zemlya Test Range on 20 October 1961. But the U.S. eventually conducted a similar test in the Pacific Ocean on 6 May 1962 with a Polaris A-2 having a W47 warhead that in the Y1 model had a design yield of 600kt launched from USS Ethan Allen SSBN-608; the Y2 model had a doubled design yield of 1.2 megaton The first Soviet SSBN with 16 missiles was the Project 667A Yankee class that entered service in 1967 with 32 boats completed by 1974, however by that time the USN had already built 41 SSBNs, designated "41 for Freedom."
The short range of the early SLBMs necessitated far-off base locations having long transit times to patrol areas but by the late 1960s the Polaris A-3 with a range of 2500 nm was deployed on all USN SSBNs, a significant improvement over the 1,000 nm range of the Polaris A-1, and the A-3 also featured three warheads that detonated in a pattern around a single target. So since the Soviet Yankee class was initially equipped with the R-27 Zyb/ss-n-6 missile with a range of just 1,300 nm the U.S. held an advantage not only in range but in its basing arrangements too because of NATO countries' cooperation and Guam being a territory of the United States. This permitted USN SSBNs to be permanently forward deployed at Advanced Refit Sites in Holy Loch Scotland, Rota Spain and Guam by the middle 1960s resulting in shorter transit times to their patrol areas near the Soviet Union. With two rotating crews, a Blue and Gold, assigned per SSBN submarine approximately one-third of the total U.S. force could operate within a patrol area at any given time, their crews were flown first class between their foreign and home bases. Contrastingly, the Soviet bases located near Murmansk for the Atlantic Fleet and the Petropavlovsk-Kamchatsky area for the Pacific required that their SSBNs make extended transits through NATO-monitored waters in order to target the continental United States (CONUS) dictating a low percentage occupancy rate of Soviet forces within their patrol areas and so was a strong motivation to develop longer-range Soviet SLBMs to permit shorter transits. Consequently, their SS-N-8 with a range of 7,700 miles entered service on the first Delta-I boat in 1972 with a total of 43 Delta-class boats to follow, then the SS-N-18 on the Delta III class and the R-29RM/Shtil SS-N-23 on the Delta IV class. The new missiles provided increased range and Multiple Independently targetable Reentry Vehicles (MIRV), multiple warheads that that could be targeted individually and carried four 100 kiloton warheads and had a range of about 5,300 mi.
Although the U.S. didn’t commission any new SSBNs between 1967 and 1981, it did project the deployment of two new missile systems and so, thirty-one of the original 41 original SSBNs had been constructed with larger diameter launch tubes to accommodate them and when in the early 1970s, the Poseidon C-3 missile entered service they were back fitted with it. Poseidon provided an immense MIRV capability of up to 14 W-68, 14 Kiloton warheads per missile and like the Soviets the U.S. also anticipated a longer-range missile that would allow SSBNs to be based closer to CONUS. Consequently, in the late 1970s the Trident I, C-4 missile with a range of 7,400 miles and eight W76 100 KT MIRV warheads was back fitted to 12 of the Poseidon-equipped submarines justifying the abandonment of the SSBN base at Rota Spain with the Naval Submarine Base King's Bay Georgia built to accommodate the new Trident submarine force.
Ensuing both the United States and the Soviet Union commissioned larger SSBN submarine designs to accommodate newer missiles in 1981 with the USN’s new SSBN being the Ohio class Trident submarine having the largest payload ever of 24 missiles. The lead ship, USS Ohio SSBN 726, was built with even larger missile tubes to accommodate the Trident II D-5 missile that entered service later in 1990 fitted either with either of 1 to 8 Mk-5 RV/W88 455 kt, or 1 to 14 Mk-4 RV/W76-0 100 kt, or 1 to 14 Mk-4A RV/W76-1 90 kt, or a single or multiple W76-2 5-7 kt warheads. Then the entire submarine class’ systems were converted to launch the Trident II by the early 2000s that achieved a range of over 8,000 miles. When Ohio commenced sea trials in 1980 two of the original ten earlier USN SSBNs had were converted to SSGN Cruise missile boats to comply with SALT treaty requirements and the remaining eight were converted to SSN attack submarines by the end of 1982. All were based in the Pacific enabling the Guam SSBN base to be disestablished because the first several Ohio-class boats were based at a new Trident facility at Naval Submarine Base Bangor Washington. Eighteen Ohio-class boats had been commissioned by 1997, four of which were converted to SSGNs in the 2000s to comply with START I treaty requirements. The Soviet’s largest SSBN was the Project 941 Akula, renowned as the Typhoon-class and not to be confused with the Project 971 Shchuka attack submarine designated "Akula" by NATO. The Typhoons were the largest submarines ever built at a submerged displacement of 48,000 tons, were armed with 20 of the new R-39 Rif, SS-N-20 missiles with a range of 8,300 miles and had 10 MIRV 100 -200kt warheads with six Typhoons commissioned 1981–89.
New SSBN construction was terminated for over 10 years in Russia and drastically reduced in the U.S. with the collapse of the Soviet Union in 1991 and the end of the Cold War and the USN rapidly decommissioned its remaining 31 older SSBNs with a few converted to alternate roles; the base at Holy Loch was disestablished. Most of the former Soviet Navy SSBN force was gradually scrapped under the provisions of the Nunn–Lugar Cooperative Treaty Reduction agreement the purpose of which was to secure and dismantle weapons of mass destruction and their associated infrastructure in the former Soviet Union states leaving the Russian SSBN force with six Delta-IVs, three Delta-IIIs, and a one Typhoon used as a test bed for new missiles, and upgraded missiles such as the R-29RMU Sineva and SS-N-23 Sineva were developed for the Deltas. Then in 2013, the Russians commissioned the first Borei/Dolgorukiy class SSBN submarine and by 2015 two others had entered service intended to replace the aging Deltas and carries 16 solid-fuel RSM-56 Bulava missiles with a reported range of 10,000 miles and 6-10 MIRV 100-150 kt MIRV warheads. The USN is currently building the new Columbia class Trident submarine to replace the aging Ohio-class whose remaining boats will be decommissioned one per year beginning in 2027. Each submarine will have 16 missile tubes carrying one new “life extended” Trident II D5LE missile.
Ballistic missile submarines have been of great strategic importance to the United States, Russia, and other nuclear powers since entering service during the Cold War because they can be hidden from reconnaissance satellites to launch nuclear weapons with impunity making them immune to a first strike and allowing each side to maintain the capability to launch a devastating retaliatory strike even if all other weapons have been destroyed. This capability is in accord with the doctrine of military strategy and the national security policy of Mutually Assured Destruction (MAD) in which a full-scale use of nuclear weapons by two or more opposing sides would cause the complete annihilation of both the attacker and the defender. It is based on the theory of deterrence which holds that the threat of using strong weapons against an enemy deters the enemy's use of those same weapons.
In addition to SLBMs, most Superpower navies deploy submarine-launched cruise missiles (SLCM) deployed on submarines usually designated as SSG or SSGN. Current versions are typically standoff weapons designated land-attack cruise missiles (LACMs) for attacking predetermined land targets with conventional or nuclear payloads or Anti-ship cruise missiles (ASCMs). The US deployed the short-range Harpoon anti-ship missile on submarines beginning in 1981. And the Soviet Navy converted 13 Project 613 Whiskey-class submarines for the land-attack LACM role in the late 1950s armed with the SS-N-3 Shaddock missile but as Soviet SSBNs armed with SLBMs became prevalent in the late 1960s, the Shaddock LACM was withdrawn and an ASCM version replaced it. Later, their Charlie and Oscar-classes were designed to use long-range ASCMs, the SS-N-9/P-120 and SS-N-19/P-700) respectively. The current Akula- and Severodvinsk-class submarines are armed with the SS-N-21/S-10 LACMs.
Four U.S. Navy Ohio-class SSBNs were converted in the mid-2000s to be able to salvo launch up to 144 Tomahawk cruise missiles from their modified vertical launch tubes, as opposed to launching cruise missiles from torpedo tubes as is done by attack submarines. Tomahawk was deployed on US Navy attack submarines beginning in 1983, originally in LACM and ASCM versions, but the ASCM version was withdrawn in the 1990s.