25 January 2010
In the late 1960s the backbone of the Soviet Union's Strategic Rocket Forces (which in the USSR was an independent branch of the military) was the UR-100 ICBM designed by noted Russian rocket designer Vladimir Chelomei. The UR-100 had the NATO designation SS-11 and the code name "Sego" and was a two-stage, liquid propellant missile with a single warhead and was of relatively low accuracy but broadly comparable to the first generation of American Minuteman ICBMs. The Sego was an attempt to reach numerical parity with the United States with a missile that was relatively easy to produce and deploy, reaching IOC with the Strategic Rocket Forces in 1966 after three years of development and flight testing.
With the deployment of the American Minuteman III ICBM which now had three MIRV (multiple independently-targetable re-entry vehicle) warheads instead of a single warhead on the Minuteman I, the Soviets needed to match this technology and in the 1970s to the amazement of US intelligence analysts, deployed three ICBM types to replace the older SS-11 Sego.
The first to reach IOC in 1974 was an upgrade of the SS-11/UR-100 Sego- the UR-100U or SS-11 Mod 3 was based on the original SS-11 design but now had three warheads but the real centerpiece of the upgrade was a newly-hardened missile silo that could better withstand a US nuclear counterstrike.
Next to reach IOC in mid-1975 was the UR-100N which had the NATO designation SS-19 and the code name "Stilleto", which was also designed by Vladimir Chelomei to replace the UR-100/SS-11 Sego missile. The Stilleto was a two-stage liquid fueled missile with six MIRV warheads.
Right behind the Stilleto in reaching IOC with the Strategic Rocket Forces was the competing design to that missile, the UR-100MR which had the NATO designation SS-17 and the code name "Spanker". The Spanker was the first Russian ICBM to be designed with MIRV warheads, having four of them and in a first for the Russians, it used a cold-launch system where compressed gases were used to eject the missile out of the silo before engine ignition. The Spanker was designed by Vladimir Chelomei's rival, Mikhail Yangel .
But the real reason three ICBM systems were fielded by the Soviet Union was that there was disagreement over nuclear strategy. Yangel's SS-17 design would need new hardened silos but offered four warheads over the SS-11's single warhead, making it an effective counterforce to insure retaliation if the USSR were attacked by the United States. However, it was the most expensive of the systems. Chelomei originally offered the upgraded SS-11 Mod 3, which would have fit in existing silos but weren't as hardened as the SS-17 design's silos. Thus, this missile offered more warheads for less money, making it a threatening first strike weapon since it would have been vulnerable to a US counterstrike.
Soviet Premier Leonid Brezhnev called a meeting at his vacation home in Yalta to resolve the dispute with the president of the Russian Academy of Sciences, Mstislav Keldysh, appointed as head of the commission to resolve the dispute and set out a clear Soviet nuclear strategy. Halfway through the meetings Chelomei offered the SS-19 with its six warheads in competition to Yangel's four-warhead SS-17 design. Keldysh lamented in his memoirs that there was a rush to build missiles but there hadn't even been a decision on a strategic nuclear doctrine.
In the end, it was decided the best path forward was to accommodate everyone's interests and that is how in the 1970s the Soviet Union's Strategic Rocket Forces ended up fielding three new ICBM systems at tremendous cost, something that would further hasten the deterioration of the Soviet economy that led the the collapse of the USSR twenty years later.
Source: The Dead Hand: The Untold Story of the Cold War Arms Race and its Dangerous Legacy by David E. Hoffman. Doubleday Books, 2009, p18-19.