point). To partially circumvent the treaty, the missile was equipped with 40 decoys to utilize the capacity left unused due to the 10-warhead limitation. These decoys would appear as warheads to any defensive system, making each missile as hard to intercept as 50 single warheads, rendering potential anti-ballistic defense ineffective. Silo hardness A US military estimate circa 1994 said "... those SS-18 silos have since been assessed to be much harder than ..." Variants R-36 (SS-9) R-36 The R-36 is a two-stage rocket powered by a liquid bipropellant, with UDMH as fuel and nitrogen tetroxide as an oxidizer. It carries one of two types of re-entry vehicles (RVs) developed especially for this missile: Single nuclear warhead of 20 megatons TNT (NATO codename SS-9 Mod 1). Single nuclear warhead of 8.3 megatons TNT (NATO codename SS-9 Mod 2). The first launch of an R-36 took place on September 28, 1963, and ended ignominiously when the missile lost thrust one second after liftoff and fell back onto the pad, causing a fire. This debacle led to program director V.P. Petrov being fired and replaced by V.N. Soloviev. LC-67/1 was repaired and the next test took place successfully on December 3. Subsequent testing went better, however, LC-80/1 had to be rebuilt following another launch accident on January 13, 1965. Two months later, an R-36 caught fire during propellant loading on LC-67/1 and exploded, putting the pad out of commission for nine months. During test launch #17 (October 10, 1964), the warhead was retrieved with a parachute. Flight tests of the rocket were completed by May 20, 1968, and on November 19 of the same year it entered service. The first (and only) regiment with 18 launchers was deployed on August 25, 1969. A total of 139 8K67s flew between 1963 and 1975 with 16 failures. The Tsyklon series of civilian space launchers from Ukraine is based on the R-36orb (8К69) or R-36-O (capital O for Orbital) design. The R-36-O launched many orbital satellites (like Cosmos 160, SATCAT 2806, on 17 May 1967) in the 1960s and 1970s as part of the FOBS weapons program. R-36M (SS-18 Mod 1) Variant of the R-36M carrying a single large reentry vehicle, with a warhead yield of 18-25 Mt, a distance of about . In January 1971, cold-launch tests began during which the mortar launch was perfected. The actual flight tests for the missile began on 21