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Development history and deployment

Lead-up to FOBS development

Some USSR officials began expressing a desire for an FOBS-type weapon around the time of Sputnik's launch. In the early 1960s, the Soviet Union felt that pursuing a system like the FOBS would be a natural next step given the belief that the US was already planning to use space to mount nuclear attacks. While it is true that American officials were researching ideas of this sort then, these inquiries tampered off by 1965.

Competing FOBS designs

Soviet rocket engineer Sergei Korolev seems to have been responsible for the first FOBS-type missile design. His offering was the GR-1; it was also known as Global Missile 1 within Korolev's design bureau, as SS-X-10 SCRAG by NATO authorities, and as 8K713 by Soviet GRAU index. Korolev's research began in 1960 and the GR-1 project was sanctioned by Soviet officials on September 24, 1962. Korolev brought up the idea of the GR-1 to Soviet Premier Nikita Khrushchev in early 1962. Soon after, Khrushchev announced that the Soviet Union was capable of utilizing "global missiles" that could fly over both the North and South Poles on their way to a target, continuing on to say that this type of weapon would render early warning radar systems practically obsolete and leave the enemy with no time to retaliate before the weapon's impact.

The GR-1 was to use the NK-9 and NK-9V as main engines. These boosters were also key to the development of the engines of the N1, the rocket of the first Soviet crewed moon landing program. Though the NK-9 and NK-9V weren't created by Korolev's team, the GR-1's 8D726 retrorocket engine was. This engine would prove to be instrumental to the progress of Russian rocketry, specifically for its importance in the development of the Blok-D upper stage of rockets like the N1, Proton, and Zenit. The GR-1 had three stages and a launch mass of 117 tons. It was 35 meters long and could carry a single nuclear warhead with a 2.2 megaton blast yield. It was cryogenic liquid propelled, utilizing a mix of RG-1 kerosene with liquid oxygen.

Two other FOBS-type missile projects emerged around the time of the GR-1's early development. It seems that each of these projects were competing with one another for usage selection and therefore there was not sustained coordination between them. It isn't known why Soviet leadership decided to pursue FOBS development in this way with three separate projects beginning all roughly within a year of one another.

The first of the two other projects was that of Soviet missile engineer Vladimir Chelomey who proposed two designs: one called the UR-200A (GRAU index 8K83) that was derivative of his UR-200 ICBM (for which development authorization was received on March 16, 1961) and another designated as GR-2 which built off of his colossal UR-500 prototype ICBM and had a much larger explosive yield of 30 megatons (for which development authorization was received on April 24, 1962). The UR-200A design was eventually selected for further development over the UR-500 version, though it isn't known why. It was to use the RD-0202 and RD-0205 engines for its first and second stages respectively. It had a launch mass of 138 tons, was 35 meters long, and was to be equipped with an AB-200 maneuvering warhead with a 5-15 megaton explosive yield. Unlike the GR-1, the UR-200A used storable (or hypergolic) liquid propellants; specifically nitrogen tetroxide and UDMH.

The second of the two other projects came from the Soviet missile designer Mikhail Yangel. His proposal was the R-36O (GRAU index 8K69) which was approved for development by Soviet officials on April 16, 1962. Yangel used an ICBM design of his own, the R-36 (NATO designation SS-9 Scarp), as a base for the R-36O. The missile had three stages, using the RD-251 engine in its first stage and the RD-252 engine in its second stage. The weapon's third stage filled a deorbiting and warhead guidance purpose that the Soviets referred to as Orbital Payload (OGCh). During this stage, an aiming system would check and rectify trajectory issues in relation to the desired target's location through the use of various instruments (for instance, a radio altimeter used in conjunction with an inertial navigation system). The guidance system would make its checks directly after the missile came into orbit and immediately before third stage ignition. Deorbiting would be induced by the missile's retrorocket, the RD-854 engine, causing the warhead to take on a ballistic path towards its target. The warhead, retrorocket, and guidance system were each contained inside the OGCh module, together comprising the R-36O's third stage. A series of nozzles on the RD-854 enabled pitch, yaw, and roll of the OGCh. Other nozzles facilitated the separation of the warhead from the rest of the OGCh, allowing it to fall alone on a ballistic path to the desired location. The R-36O's explosive yield was between 5-20 megatons according to Soviet sources. Western intelligence suggests that the yield was smaller, being somewhere between 1-3.5 megatons. The missile was roughly 33 meters long and had a launch mass of 180 tons. The R-36O used the same hypergolic propellants as the UR-200A.

Yangel design selection

In 1965, Soviet military officials worked to select one of the three orbital weapon system projects. The R-36O of Yangel's design bureau was chosen for further development over the others. The reasoning behind the Soviet FOBS design selection process remains somewhat unclear. A particularly confounding factor to consider is that none of the three proposed missiles had undergone a single test flight prior to the R-36O's selection. Even so, there are some explanations as to why Yangel's design was chosen in the end. These revolve around the occurrence of negative events in the competing GR-1 and UR-200A projects that effectively knocked them out of contention; this recounting thus suggests that the R-36O was selected because it was the last viable FOBS project the Soviet Union had left.

One strike against Korolev's GR-1 was that it used a cryogenic propellant, thereby rendering the missile a poor candidate for operational storage in a missile silo as the Soviet military desired. Moreover, just as the GR-1 was being developed, a different project of Korolev's design bureau, that of the R-9A ICBM, was experiencing a string of difficulties in its testing phase. The GR-1's 8D726 retrorocket was already demonstrating a similar proclivity for failure in its initial tests and, as a cause for yet more worry, the troublesome R-9A shared many of its physical components with the GR-1; thus, military leadership was encouraged to look elsewhere for more immediate progress. The GR-1's ability to deal with US ABM systems and its lengthy fueling process were also questioned by Soviet analysts. Under the weight of these issues, the GR-1 project was officially canceled in January 1965.

Chelomey's UR-200A project lost a great deal of support after Khrushchev, his most important political ally, was ousted in 1964. Worse still, his UR-200 ICBM project (this missile providing the basis for the UR-200A) had already been canceled. Having lost the ability to tap into the Soviet Premier's influence, Chelomey ultimately failed to secure the survival of the UR-200's FOBS offshoot, the UR-200A's development coming to an end in 1965.

Flight testing and deployment

At its missile range near Baikonur, Kazakhstan, the Soviet Union built a structural foundation for testing and deploying the R-36O. To begin with, a testing station and a horizontal assembly facility were constructed for the missile's development. Over most of 1965, two R-36 test pads were modified to work with the R-36O for its early test flights. In addition, 18 silos capable of launching the R-36O were built over the mid 1960s to 1971; three rounds of construction occurred with six silos being built each time. Those built at the same site were placed 10-15 kilometers away from one another to prevent the possibility of a single nuclear strike destroying multiple silos.

The Soviet Union originally planned nineteen R-36O launches, but 24 were carried out by 1971. The initial four were to begin from a ground-based testing pad and then fly to the Kamchatka Peninsula. The other tests called for the R-36O to be launched from a silo into orbit where it would then execute its third stage deorbit process over the Pacific Ocean; the missile's payload would be retrofired into Soviet territory. Over 2000 Soviet service people participated in the tests. Six of the tests were outright failures while the others achieved either complete or partial success. Prior to the first launches, the Soviet Union stated that a "space vehicle landing system" was being tested over the Pacific.

The first test flight occurred on December 16, 1965. It missed the landing area by a wide margin owing to a stabilization instrument malfunction. The second test was on February 5, 1966 and was also a failure due to a retrorocket issue. The third test took place on March 16, 1966. Nitrogen tetroxide spilled over the surface pad during fueling due to a miscommunication and the missile was quickly destroyed by fire. Some success was had with the fourth test on May 20, 1966, but the payload didn't break away from the missile's guidance system as intended. The following tests were conducted from silos. The first two tests of the silo phase ended in the intentional destruction (via self-destruct functionality) of the R-36O as a result of the second stage engine accidentally being activated for too long, sending the payload into an unplanned orbit. NATO radar systems picked up on the large mass of resulting debris. In one failed test case, small pieces of the missile rained down on the midwestern United States.

In 1967, the Soviet Union conducted ten more R-36O tests, nine of them seeing some level of success. In that year and beyond, the Soviet Union used public statements about satellite launch tests as cover for any R-36O test that was intended to put its payload in orbit for some period of time.

On November 19, 1968, about a month after the 20th test, the Soviet Union designated the R-36O as operational and began its deployment in three groups of six. By 1971, all 18 of the Soviet Union's R-36O silos were in service in Kazakhstan. NATO intelligence suggests that a primary target was the US Grand Forks Air Force Base where an ABM system was set to be established in the late 1960s to early 1970s. The R-36O wasn't equipped with a nuclear payload until 1972.

Reasons for development

The Soviet Union identified a number of strategic advantages of the FOBS. The following points prompted its development:

• The system granted virtually unlimited striking range with a nuclear weapon.
• The system allowed a strike to be carried out from multiple directions. For instance, the Soviet Union could launch an attack against the United States using a South Pole or North Pole flight path; technically, it could even execute both of these attack plans simultaneously.
• The system provided a way of evading early warning radar systems. This advantage comes from two different attributes of the FOBS: (1) that it could attack from any direction, as stated above, and (2) that it could travel along a very low Earth orbital path. The first point has to do with the fact that the primary missile defense radar system of the US around the time of the FOBS' early development was the Ballistic Missile Early Warning System (BMEWS). The BMEWS was oriented to detect ballistic missiles coming from the aforementioned 'North Pole route' (its three stations being located in Alaska, Greenland, and the United Kingdom) and therefore wouldn't detect a strike flying along a southern orbital path. The second point considers that FOBS missiles could fly relatively close to the Earth's surface; they could have a perigee of under 100 miles and an apogee as low as 125 miles above the ground (see apsis). US radar systems like the BMEWS were configured to detect ICBMs that flew several hundred to upwards of 1000 miles above the surface, not low altitude missiles like that of the FOBS. Thus, the Soviet Union felt that striking with a FOBS would deprive the United States of valuable warning time that ICBMs were likely to give away (this being around 15 minutes, enough to mount a devastating retaliatory attack).
• The system concealed the target location until the payload was dropped out of orbit. Theoretically, the FOBS was capable of staying in orbit indefinitely and could separate its warhead from the FOBS vehicle at any given point in the orbit.
• The FOBS' flight duration was shorter than that of an ICBM (assuming an indirect route isn't taken for the purpose of radar evasion). An FOBS missile may have been able to reach its target around 10 minutes before an ICBM would.
• The Soviet Union supposed that the FOBS would be capable of trumping US anti-ballistic missile (ABM) systems. This was actually a primary objective of the Soviet FOBS from its origin. On one hand, the FOBS was seen as a tool that could clear the way for a Soviet ICBM strike, boosting its effectiveness by first eliminating some of the enemy's safeguards. It was also thought that the FOBS would be able to evade US ABMs.

End of deployment and associated reasons

There are two main technical disadvantages of the FOBS to consider:

1. Its nuclear payload was drastically reduced relative to that of an ICBM due to the high level of energy needed to get the weapon into orbit. According to American intelligence, the FOBS' nuclear warhead mass needed to be roughly 1/2 to 1/3 of that of an ICBM.
2. The FOBS was less accurate than an ICBM. This was empirically demonstrated in the series of Soviet R-36O flight tests that occurred over 1965-1971.

There are a number of other factors to consider that prompted the end of FOBS deployment in the Soviet Union:

• The FOBS wouldn't be able to overcome later early warning radar system developments made by the US, especially those that came in the form of space-based radar deployments. The US established missile detection systems of this type by the early 1970s. The FOBS was made to counter relatively simple ground-based systems like the BMEWS, not the more expansive radar network that followed it. The Soviet FOBS thus had lost one of its primary capabilities only several years into its deployment, an FOBS strike no longer having an adequate probability of going undetected by the US.
• An additional primary use of the Soviet FOBS—its ability to counter an American ABM system—was found out to be needless as time passed. Contrary to earlier Soviet projections, the US never built a large ABM system purposed in destroying incoming Soviet ICBMs. The only significant American ABM system constructed was Safeguard (initially called Sentinel), but it was shut down by 1976 and would have been practically useless in the face of anything beyond a limited Soviet ICBM attack.
• Soviet SLBM technology grew into a good replacement for the FOBS on the basis of low flight time, high range (via the submarine's ability to move near its target), and the element of surprise.
• The FOBS potentially acted as a dangerous accelerant to the Cold War arms race for the reason that it was most useful in the context of a pre-emptive nuclear strike. A nation observing their enemy developing the FOBS could logically conclude that they viewed a first strike as a viable nuclear strategy; the observing nation may react to this realization by ramping up its own weapon production and perhaps adopting a first strike nuclear strategy as well.

Soviet FOBS deployment began to come to an end in January 1983. The R36-O missile was completely removed from service by February of that year. Starting in May 1984, the Soviet Union razed its FOBS-capable silos. There's confusion over whether all 18 silos were destroyed. One source suggests that six silos were instead modified for the purpose of ICBM modernization testing, as per a SALT II agreement (see the 'Outer Space Treaty and SALT II' section).

Outer Space Treaty and SALT II

Article IV of the Outer Space Treaty of 1967 stated that:

Parties to the Treaty undertake not to place in orbit around the Earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner.

The overriding opinion of US administrators was that the Soviet FOBS did not violate the treaty, mostly for the reason that the system didn't go into a full orbit. For instance, US Secretary of Defense Robert McNamara argued that the Soviet Union had only agreed "not to place [nuclear] warheads in orbit," continuing on to point out that the FOBS executes its mission on a "fractional orbit, not a full orbit." Senator Henry M. Jackson, chairman of the Joint Atomic Energy Subcommittee on Military Applications, countered that the Soviet FOBS was at least a "good faith violation of the treaty," alluding to the notion that the weapon could go into orbit. This is certainly true: the only thing stopping the Soviet FOBS' payload from completing a full revolution around the Earth (and thereby literally going orbital and violating the treaty) was the firing of the system's retrorocket. Even so, McNamara also drew attention to the fact that the treaty didn't ban any form of weapons testing—not even the testing of an orbital nuclear weapons system. None of the Soviet Union's test R-36Os were ever equipped with a nuclear warhead; so, even if it were the case that the launches went orbital, they still wouldn't have broken the treaty.

Unlike the Outer Space Treaty, the SALT II agreement of 1979 explicitly prohibited the pursuance and deployment of the FOBS:

Each Party undertakes not to develop, test, or deploy:

(...)

(c) systems for placing into Earth orbit nuclear weapons or any other kind of weapons of mass destruction, including fractional orbital missiles;

The SALT II agreement was never ratified by the United States Senate. The Soviet Union ultimately complied with its terms anyway, decommissioning its FOBS in 1983 (see End of deployment and associated reasons). The agreement also stipulated that 12 of the 18 Soviet FOBS launchers in Kazakhstan were to be taken apart or demolished and never replaced. This was meant to happen within an eight month period following the treaty's ratification. The terms allowed the USSR to modify the six remaining launchers to fit missile modernization testing purposes.

American view

As early as 1962, the United States Central Intelligence Agency (CIA) suspected that the Soviet Union would develop a space-oriented bombardment system like the FOBS. However, the US perspective was that FOBS-type weapons didn't offer any meaningful advantages over the ICBM. American officials thus initially found no reason to pursue orbital weapon development nor believe that the Soviet Union was intending to deploy such a weapon in any militarily significant capacity, supposing that the Soviets intended to use this technology for "propaganda or political reasons" if anything. The CIA made note of the Soviet Union's R-36O test launches and realized that they were more serious about the military applications of an FOBS-type weapon than originally expected. Still, by October 1968, around a month before the R-36O was declared operational by the USSR, it remained unclear to the CIA whether the tests they had observed involved an FOBS or a "depressed trajectory" ICBM.

Prior to this report, the CIA had higher confidence in their belief that FOBS development was taking place in the USSR. This assessment prompted Secretary of Defense McNamara to announce that the Soviet Union was possibly creating a FOBS at a news conference on November 3, 1967. This was the first time that the FOBS project had ever been explicitly referred to in public (though Khrushchev alluded to this kind of weapon in the early 1960s). McNamara emphasized that the potential Soviet FOBS did not worry him in consideration of its disadvantages compared to the ICBM. At a congressional hearing soon after, John S. Foster Jr., Director of Defense Research and Engineering, stated that the US had been developing "over-the-horizon" radar networks capable of detecting a FOBS since 1963; these radars were designed to give approximately thirty minutes warning time in the case of an FOBS strike. He went on to say that the US would continue to allocate significant funding to early warning radar projects of this sort.

It can be noted that the US' view that the FOBS wasn't particularly useful is a possible explanation as to why the Soviet FOBS was defended by McNamara and others in the context of the 1967 Outer Space Treaty. The idea is that they weren't willing to see the treaty break down over a single issue like the FOBS, especially given that they had already evaluated it as a minor threat in the grand scheme of that period's nuclear weapon landscape.

References

Description:

Leading up to nuclear arsenal negotiations set to take place in Geneva in January 1985 between U.S. Secretary of State George Shultz and USSR Minister of Foreign Affairs Andrei Gromyko, Reagan stated to the public that the Soviets had created the FOBS in the 1960s. The decision to announce this information was reportedly motivated by a US-Soviet propaganda battle: the Reagan administration desired to portray Soviet arms buildup in space as prompting the U.S. to pursue a space buildup of its own (for example, in the form of the Strategic Defense Initiative) instead of the other way around, as the USSR's narrative went.

Description:

On November 3, 1967, U.S. Secretary of Defense Robert McNamara stated during a news conference that it was believed by US intelligence authorities that the USSR was in the process of developing the FOBS. Days later, it was discussed in a Joint Committee on Atomic Energy hearing whether the FOBS was capable of eliminating US ABM systems (such as Nike-X and the then proposed Sentinel). John S. Foster Jr., then Director of Defense Research and Engineering, claimed that US ABMs could be adapted to counter the Soviet FOBS. Some at the congressional hearing reacted to news of the possibility of the Soviet FOBS by reemphasizing their support for the establishment of an expansive anti-Soviet ABM defense system. At that point, the US presidential administration had only advocated for limited ABM defense intended to counter Chinese ICBMs. McNamara and others within the administration felt that Soviet-oriented ABM defense buildup would only serve to spur increased offensive arms buildup between both the USSR and the US; as Deputy Secretary of Defense Paul Nitze stated, there was no practical level of ABM proliferation that could successfully defend against the nuclear capabilities of the Soviet Union.

Foster also stated that the USSR had initiated its FOBS project around 1963. The US chose not to build a FOBS, instead opting for the development of radar systems that could detect incoming FOBS strikes relatively early on. Foster continued on to say that the US was planning to spend increasingly more to improve its FOBS detection capabilities. Foster ended by giving three reasons why the US didn't seek to obtain a FOBS: the system's near-orbital conveyance 1) necessitated a severely diminished payload 2) reduced its accuracy, and 3) hindered its coordinated strike abilities.

The congressional hearing also came to the topic of whether the FOBS was illegal under the Outer Space Treaty of 1967 (particularly Article IV which banned the placement of nuclear weapons in Earth's orbit).

McNamara announcing FOBS development possibility on November 3, 1967:

FOBS attack follows low Earth orbit path, ~100 miles above the surface. A rocket then slows the missile's payload until it falls out of orbit and takes a ballistic missile-like path to the ground.

It's said that the attack could be carried out with traditional Soviet ICBMs like the SS-7 and SS-8.

Nine short Soviet test flights were reported to have occurred from Sept. 17, 1966 to Oct. 28, 1967, at least some of which US intelligence authorities thought had to do with FOBS development.

Stated pros of FOBS during announcement:

FOBS attack can't be detected by some radar systems due to low flight route.

Target can't be known exactly until the payload falls out of orbit.

Flight duration can be around 10 minutes shorter than that of an ICBM.

Can hit the US from the Southern Hemisphere, dodging radar.

Description:

McNamara's reasons for why potential FOBS testing by the Soviet Union didn't break the Outer Space Treaty of 1967:

1) No nuclear warhead was equipped to the testing vehicles (so certainly no nuclear weapon went into orbit).

2) The test didn't actually complete a full orbit (the test 'payload' fell out of orbit before one could be completed; hence, the fractional component of the name).

3) The treaty doesn't stipulate that any weapons can't be developed.

Description:

The earliest estimations place the Soviet FOBS project start date in 1962.

One reason that the Soviets stopped working on the project was due to accuracy issues. This article makes the argument that the Soviets were indeed able to deploy nuclear weapons through a FOBS; that they could even leave a nuclear warhead in permanent orbit with the launching and guidance technology they had in the 1960s.

Description:

Cites another pro for the FOBS: ability to attack from virtually anywhere in orbit.

Con of FOBS: payload very small relative to ICBM (mentioned by Foster in 2).

Says that US is making an over-the-horizon radar system to give approx 30 minutes warning of FOBS strike (this is mentioned by Foster in 2). A new 3-stage Spartan ABM was intended to destroy incoming missiles like that from a FOBS.

Summarizes McNamara's response as to if the USSR could put a nuclear weapon in orbit indefinitely (until the desire to strike arises):

Says that they can.

1) This would be a clear violation of the Outer Space Treaty of 1967.

2) The weapon would be easily detected and destroyed, being very exposed.

Description:

SALT II of 1979 fills the loophole of the Outer Space Treaty of 1967 by explicitly mentioning the ban of fractional orbit weapons systems.

Description:

The Soviets only built 18 launchers for their FOBS.

Description:

The existence of the FOBS system wasn't explicitly made public knowledge by the Soviet Union (though we see in the Fordham source that the Soviet Premier did speak generally about it years before). Secretary of Defense McNamara was actually the first to publicize it in November 1967 (pg 663).

The FOBS would be launched into orbit with a traditional ICBM (like the SS-7, SS-8, or SS-9). The vehicle containing the nuclear weapon would be around 5000 kilograms. At perigee, the weapon would be 86-97 miles from the Earth's surface. At apogee, it would be 127-183 miles from the surface. Before a full orbit was completed and when it was some 500 miles away from the desired target, the system was to fire a retrorocket to slow the weapon down, making it fall out of orbit onto the designated area (pg 663).

FOBS testing occurred seventeen times from September 1966-August 1971. In one case, the weapon broke apart during flight, raining down fragments on the midwestern United States (pg 663-664).

The Soviet Union erected eighteen FOBS launching silos at a site near Baikonur, Kazakhstan. NATO intelligence suggests that these silos were prepared to strike the US Grand Forks Air Force Base where an ABM system was set to be constructed in the late 60s to early 70s (pg 664).

One of the primary advantages of the Soviet FOBS was that it could mount a nuclear strike via a South Pole route instead of going over the Arctic, thereby evading the US's North Pole oriented Ballistic Missile Early Warning System. Once US radar coverage expanded, the usefulness of the FOBS faded for the Soviets. This radar evolution could be a primary reason why the USSR stopped conducting tests for the project in the early 1970s and put up virtually no resistance when asked to dismantle its FOBS silos under the SALT II Treaty (pg 664).

Description:

The SALT II treaty stipulated that twelve of the eighteen Soviet FOBS launchers in Kazakhstan were to be taken apart or demolished and never replaced. This was to happen within an eight month period following the treaty's ratification. The USSR was to be allowed to modify the six remaining launchers to fit missile modernization testing purposes.

Description:

The term 'Fractional Orbital Bombardment System' is actually the NATO intelligence term for this weapons system. The term used by the Soviet Union during development hasn't been revealed.

The talks that led up to the initiation of the FOBS project within the Soviet military were generally shrouded in secrecy, though it is known that some USSR officials had expressed a desire for such a weapon following the launch of Sputnik. In the early 1960s, the Soviet Union felt that pursuing a system like the FOBS would be a natural next step given the belief that the US was already planning to use space to mount nuclear attacks; it is true that American officials were researching ideas of this sort then, though these studies tampered off by 1965.

Soviet Union listed the following as advantages of the FOBS:

1) Unlimited striking range.

2) Ability to hit the same target from multiple directions.

3) Low flight time relative to ICBMs (assuming an indirect route isn't taken for the purpose of radar evasion).

4) The fact that the desired target remains unknown to the enemy all the way until the point when the bomb falls out of orbit.

5) The potentiality of considerable accuracy even given a long flight path.

6) The difficulty that US ABM systems would have with destroying this weapon.

In addition to the FOBS' ability to evade the Arctic-oriented Ballistic Missile Early Warning System (BMEWS) by flying in a fractional orbit over the South Pole to strike the US, the FOBS' low altitude flight path would make it difficult to detect by radar even if an Arctic route strike was carried out. Early US radar systems were configured to detect ICBMs which would fly several hundred to upwards of one thousand miles in the air, not missiles flying at altitudes of around one hundred miles, as the FOBS was capable of. Thus, the Soviet Union felt that striking with a FOBS would deprive the United States of the valuable warning time that ICBMs were likely to give (this being around 15 minutes, plenty of time to mount a retaliatory attack).

Soviet rocket engineer Sergei Korolev seems to have been responsible for the first FOBS-type missile design, his research on the GR-1 (Global Missile 1) starting in 1960. Korolev's project was sanctioned by Soviet officials on September 24, 1962. Two other FOBS-type missile projects emerged around this time period. It seems that each of these projects were competing with one another for usage selection and therefore there was not sustained coordination between them. It isn't known why Soviet leadership decided to pursue FOBS development in this way with three distinct projects beginning all roughly within a year of one another.

Korolev's GR-1 was to use the NK-9 and NK-9V engines which he also intended to iterate on for development of the N1's engines, the rocket of the first Soviet crewed moon-landing program. The GR-1's retrorocket engine was the 8D726. The weapon weighed 117 tons in total and its warhead had a 2.2 megaton blast yield.

Korolev brought up the idea of the GR-1 to Soviet Premier Nikita Khrushchev in 1962. Soon after, Khrushchev announced that the Soviet Union was capable of utilizing "global missiles" that could fly over both the North and South Poles on their way to a target, continuing on to say that this type of weapon would render early warning radar systems practically obsolete and leave the enemy with no time to retaliate before the weapon's impact (see FAS R-36O Source for longer quote).

The first of the two other projects was that of Soviet missile engineer Vladimir Chelomey who proposed two designs: one called the UR-200A that was based upon his UR-200 ICBM (development authorization was received on March 16, 1961) and another designated as GR-2 which built off of his UR-500 ICBM and carried a much larger explosive yield of 30 megatons (development authorization was received on April 24, 1962). The UR-200A design was eventually selected for further development over the larger UR-500 version, though it isn't known why. It was to have two stages and use the RD-0202 ( for stage one) and RD-0205 engines (for stage two). Furthermore, the UR-200A was meant to be equipped with an AB-200 maneuvering warhead.

The second of the two other projects came from the missile designer Mikhail Yangel. His proposed missile was the R-36O which was approved for development by Soviet officials on April 16, 1962. Yangel used an ICBM design of his own, the R-36, as a base for the R-36O. The R-36O had three stages. It used the RD-251 engine in its first stage and the RD-252 engine in its second stage. The weapon's third stage filled a deorbiting and warhead guidance purpose that the Soviets referred to as Orbital Payload (OGCh). During this stage, an aiming system would check and rectify trajectory issues in relation to the desired target's location through the use of various instruments (for instance, a radio altimeter used in conjunction with an inertial navigation system). Deorbiting would be induced by the use of the RD-854 engine as a retrorocket, causing the warhead to take on a ballistic path towards its target. The R-36O's explosive yield was between 5-20 megatons according to Soviet sources. Western intelligence suggests that the yield was smaller, being somewhere between 1-3.5 megatons.

In 1965, Soviet military officials analyzed which of the three orbital weapon system projects was the best despite the fact that none of them had conducted a test flight at that point. The R-36O design was chosen for further development over the others.

One strike against Korolev's GR-1 project was that it ran off of cryogenic fuels, thereby rendering the missile a poor candidate for storage in a missile silo as the military desired. Moreover, the GR-1's 8D726 retrorocket engine appeared to be unreliable in its initial ground tests. At the same time, Korolev's R-9A ICBM project was experiencing a string of testing phase failures. Since his R-9A and GR-1 projects used many of the same physical components, military leadership was encouraged to look elsewhere for immediate orbital missile progress. Further problems included disputes over the GR-1's ability to evade US ABM systems and refueling time lags. Though the GR-1 project was officially canceled in early 1965, its 8D726 retrorocket would later prove to be useful in the development of multiple rockets, including the N1, Proton, and Zenit.

Chelomey's UR-200A project lost a great deal of support after Khrushchev, his most important political ally, was ousted in 1964. Worse still, his UR-200 ICBM project (this missile providing the basis for the UR-200A) had already been canceled. Having lost his main political connection, Chelomey faired poorly in advocating for the survival of the UR-200's orbital missile offshoot.

There's a section describing the mission profile of the R-36O.

At its Tyuratam missile range, the Soviet Union built a structural foundation for testing and launching the R-36O. Multiple testing pads and stations as well as a horizontal assembly facility were constructed for the orbital missile's development. Some R-36 test pads were modified to work with the R-36O. In total, eighteen operational R-36O launching silos were built over the mid 1960s to early 1970s. They were placed 10-15 kilometers away from one another to prevent the possibility of a single nuclear strike destroying multiple silos.

The Soviet Union originally planned 19 R-36O launches, but 24 were carried out by 1971. The initial four were to begin from a ground-based testing pad and then fly to the Kamchatka Peninsula. The other test R-36Os were to be launched from silos into orbit and then drop out of orbit over the Pacific Ocean. Over 2000 Soviet service people participated in the tests. Six of the tests were total failures while the others had varying degrees of success.

The first test was conducted on December 16, 1965. It missed the landing target by 27 kilometers, owing to a stabilization instrument malfunction. The second test was on February 5, 1966 and was also a failure due to a retrorocket issue. The third test took place on March 16, 1966. Nitrogen tetroxide spilled over the surface pad during fueling due to a miscommunication and the missile was quickly destroyed by fire. Some success was had with the fourth test on May 20, 1966, but the payload didn't break away from the guidance system as intended. The following tests were conducted from silos as planned. The first two tests saw their missiles be intentionally destroyed (via self-destruct functionality) as a result of their second-stage engines accidentally being activated for too long, sending the payloads into an unplanned orbit; NATO radar systems picked up on the resulting debris.

In 1967, the Soviet Union conducted ten more R-36O tests, nine of them seeing some level of success. McNamara made a public statement supposing that these tests had a FOBS-type purpose in early November of that year. The Soviet Union would announce that they were conducting satellite launch tests prior to a R-36O test that was intended to go orbital.

On November 19, 1968, about a month after the 20th test, the Soviet Union designated the R-36O as operational. However, they weren't equipped with nuclear payloads until 1972.

In compliance with the SALT II Treaty of 1979, the Soviet Union moved to end its R-36O project starting in 1982. It decommissioned its last R-36O in February 1983. By 1984, all of its R-36O facilities had been razed.

A list of reasons regarding strategic disadvantages of the FOBS and new improvements that rendered it less useful follows:

1) The FOBS wouldn't be able to bypass later radar developments made by the US; it would be useful against ground-based radar systems like the BMEWS, but the US had already moved on to establishing radar systems in space during the 1970s that would've detected FOBS strikes quickly and with a high success rate.

2) The 1970s also saw the Soviet Union make significant strides in nuclear submarine technology. By then, they had SLBMs which made a good replacement for FOBS; they could launch from virtually anywhere, offered the element of surprise, and had a low flight time comparable to FOBS.

3) The development of FOBS potentially served to accelerate the arms race and make nuclear war more likely given that it was mainly purposed in granting first strike capability.

4) The Soviet Union also thought to use the FOBS to take out a US ABM system, but the US didn't create an expansive one as once predicted (only one such system, Safeguard, was operational for a brief period in the 1970s and it was neither national in scope nor Soviet-oriented).

5) The FOBS' nuclear warhead had to be made significantly smaller than that of an ICBM in order to get the FOBS device into orbit.

6) The two dozen Soviet tests with the R-36O empirically show that the FOBS is less accurate than an ICBM.

None of the tested R-36Os ever carried nuclear warheads; they also never made a complete orbit (though clearly they could have if not for the intentional deorbiting) --> complies with the Outer Space Treaty of 1967. The treaty also didn't rule against testing/development of FOBS-type weapons.

As early as 1962, the CIA believed that the Soviet Union was developing an orbital weapon like the FOBS. The US perspective was that ICBMs were superior, so there was no reason to pursue FOBS development nor believe that the Soviet Union was intending to deploy an orbital weapons system in any serious way. The CIA realized that this assumption was wrong after observing the multitude of R-36O test launches in the mid to later 1960s.

See pg. 11 of the PDF for a table of R-36O test launch dates and descriptions.

Description:

Contains GR-1 specifications.

Cites "engine delays" as a reason for the cancellation of Korolev's GR-1 project. Mentions the ousting of Khrushchev as a reason for Chelomey's UR-200A project ending.

Notes the apparent development "competition" surrounding the FOBS project as a whole. Says that Korolev's GR-1 would use the same launch facilities as the R-9A. GR-1 could be used as a ballistic or orbital missile. The GR-1 was paraded in Moscow in 1965 despite having been canceled by then and never test flown.

Description:

Considers that a natural corollary to the Soviet Union's early success with launching satellites into orbit was to see if it is possible to do the same thing with a nuclear weapon, the thought being that this would grant them offensive nuclear superiority over the US.

Contains the "global missile" quote from Khrushchev in 1962.

Contains R-36O specifications.

Says R-36O is "ineffective against hardened targets" due to lower payload and accuracy.

By 1968, it wasn't evident to the CIA whether the Soviet R-36O tests concerned FOBS or low trajectory ICBMs equipped with retrorockets (see also, CIA document).