This page is under development.
See also Multimegaton Tests: the largest nuclear tests.
Contents:
High-yield thermonuclear weapons: overview
The United States and the Soviet Union, after independently developing thermonuclear weapons, both produced some numbers of such weapons of very high yield. While most thermonuclear weapons built had yields in the range of several hundred kilotons to a few megatons, some much larger weapons were built. Weapons with yields up to 20-50 megatons were developed and deployed (one Soviet weapon of 150 mt was developed but probably never operational). Of the roughly 135,000 warheads ever built by the two superpowers, about 3% had yields over 4.5 megatons.
The United States built the greater number of multimegaton weapons, doing so in the late 1950s and 1960s mostly to equip its bomber force with a massive nuclear capability against the U.S.S.R. The U.S. largely abandoned such weapons in favor of smaller nuclear weapons, allowing more flexible delivery of larger numbers of warheads. Most of the Soviet strategic nuclear capability was in its ICBMs, but like the U.S. the Soviets deployed high-yield weapons before mostly shifting to smaller, multiple warheads.
The U.S. has now retired all of its multimegaton weapons. Disassembly of the last type removed from service, the B53, may be completed in 2006. Russia probably maintains a small number ICBMs in high-yield single warhead versions. The People's Republic of China has one type of ICBM armed with high-yield warheads. Operational multimegaton weapons in 2005 thus include:
There is still considerable uncertainty on some of the issues discussed here. While much information on U.S. nuclear warhead history is available, information is still scanty on some high-yield nuclear weapons. Information now available on the former Soviet/current Russian arsenal is limited regarding its largest weapons, and considerable inconsistencies in available information remain.
The following graphs provide estimates of the total numbers and yield of U.S./Soviet/Russian high-yield weapons (those with individual yields over 4.5 megatons). Note that these estimates are based on models of stockpile history, and that total stockpile numbers and yields may not correspond to other figures on this web site.
The U.S. and U.S.S.R. have conducted a total of 23 nuclear tests of at least 4 megatons each. The U.S. from 1952 to 1962 detonated 11 such devices above ground plus one underground in 1971. The total yield of these was 105 mt for an average of 9 mt each. The largest of these was a 15 mt test in 1954. In turn, the U.S.S.R. detonated 12 such multi-megaton devices above ground in 1961 and 1962, plus one underground in 1973. Their total yield was 200 mt, for an average of 15 mt each. The largest Soviet test was a 58 mt test in 1961. The total fission yield of all 22 above ground tests was about 124 mt (54 mt from U.S. tests and 70 mt from Soviet tests).
U.S. nuclear warheads with yield over 4.5 megatons
| warhead (system) | type of system | stock entry | IOC | off alert | retired | warhead type | weight (kg) | yield (mt) | no. built |
|---|---|---|---|---|---|---|---|---|---|
| EC14 | NGB | Feb 1954 | Feb 1954 | Oct 1954 | Oct 1954 | 2-stage TN | 13133 | 6.9 | 5 |
| EC16 | NGB | Mar 1954 | Mar 1954 | Apr 1954 | Apr 1954 | 2-stage TN, standard | ~17000? | 7.5 | 5 |
| EC17 | NGB | May 1954 | May 1954 | Nov 1954 | Nov 1954 | 2-stage TN | 18900 | 11 | 5 |
| Mk-17 | NGB | Oct 1954 | Oct 1954 | 1957 | Oct 1957 | 2-stage TN | 18900 | ~12.5 | 200 |
| B21 | NGB | Dec 1955 | 1956 | 1957 | Nov 1957 | 2-stage TN, clean | 7000 | 4.5 | 275 |
| 2-stage TN, dirty | |||||||||
| EC24 | NGB | Apr 1954 | Apr 1954 | Nov 1954 | Nov 1954 | 2-stage TN | 18900 | 13.5 | 10 |
| Mk-24 | NGB | Oct 1954 | Oct 1954 | 1956 | Oct 1956 | 2-stage TN | 18900 | ~15 | 105 |
| B27 | NGB | Nov 1958 | 1958 | 1964 | Jul 1964 | 2-stage TN, dirty | 1430 | ~5 | 700 |
| B36 Y1 | NGB | Apr 1956 | 1956 | ~1961 | Jan 1962 | 2-stage TN, dirty | 7900 | 9.5 | 940 |
| B36 Y2 | 2-stage TN, clean | 6 | |||||||
| B41 Y1 | NGB | Sep 1960 | 1960 | 1976 | Jul 1976 | 3-stage TN, dirty | 4840 | ~25 | 500 |
| B41 Y2 | 3-stage TN, clean | ~9.3 | |||||||
| B53 Y1 | NGB | Aug 1962 | ~Oct 1962 | 1997 | 2006 | 2-stage TN, dirty | 4010 | 9 | 340 |
| B53 Y2 | Jun 1964 | ~1964 | ? | ? | 2-stage TN, clean | 3860 | ? | ||
| W53 (Titan II) | ICBM | Dec 1962 | Apr 1963 | May 1987 | ~1988 | 2-stage TN | 3690 | 9 | 60 |
| W71 (Spartan) | ABM | Jul 1974 | Apr 1975 | Nov 1975 | 1995 | 2-stage TN, enhanced x-ray | 1290 | ~4.8 | 39 |
Explanation: IOC=initial operational capability, NGB=nuclear gravity bomb, ICBM=intercontinental ballistic missile, ABM=antiballistic missile, TN=thermonuclear, clean/dirty refers to low/high fission yield fraction, respectively. See text for sources.
The largest U.S. nuclear weapon
(Image: Mk-17/24 bomb casing at the National Atomic Museum.)
The largest nuclear weapons ever built by the United States were the EC17/Mk-17, the EC24/Mk-24, and the B41 (Mk41). Public domain information does not allow a conclusive determination as to which had the largest yield. However, current best estimate is that the highest yield weapon was a version of the B41 with a yield of 25 mt.
The Mk-17 and Mk-24 were virtually identical weapons: they used different primaries, but were indistiguishable by external appearance and weight.[1] "Emergency capability" versions of both bombs (the EC17 and EC24) were briefly stockpiled in small numbers rushed into service in 1954. These were retired in late 1954 when the production versions were deployed.[1,2] At 18.9 metric tons each and 7.5 meters long, only the B-36 bomber could carry these weapons. All were retired by 1957 in favor of smaller weapons that could be carried by a variety of bombers.[1]
Reported yields for the Mk-17 and Mk-24 range from 10 mt to 20 mt. Chuck Hansen gave figures of 15-20 mt[1] or 10-15 mt for production versions (for the emergency capability versions he gives 11 mt for the EC17 and 13.5 mt for the EC24)[3]; NRDC reports 10-15 mt.[4] Nuclear test yields include 11 mt for the EC17 in shot Castle Romeo on 27 March 1954 and 13.5 mt for the EC24 in shot Castle Yankee on 5 May 1954.[5] Based on this the best estimates here are yields of 11 mt for the EC17, ~12.5 mt for the Mk-17, 13.5 mt for the EC24, and ~15 mt for the Mk-24.
The Mk-41 was the only three-stage thermonuclear weapon ever deployed by the U.S. It weighed 4,840 kilograms and was 3.8 meters long.[6] It could be carried by the B-52 or the B-47.[7] While about 500 were built from September 1960 to June 1962, retirement began in November 1963 and the last B41s withdrawn in July 1976.[6]
Best estimate here is that the B41 was produced in at least two versions, one of which had a yield of 25 mt--the highest yield weapon ever built by the U.S. It is likely that only a small fraction of the weapons built were the high yield version, and that these were the first ones retired (in the 1960s). These conclusions are based on the following:
The first U.S. multi-megaton weapons
Following the first Soviet nuclear test in August 1949, U.S. President Truman directed continued development of thermonuclear weapons in a January 1950 directive. The first such weapon designed used liquid deuterium as fusion fuel--necessarily cooled to temperatures near absolute zero to keep it in a liquid state. Such weapons were difficult to handle not only because of their extremely large size, but also because of the special cryogenic requirements.[11, 12]
The first multistage thermonuclear test was Ivy Mike on 1 November 1952: far from being a deliverable weapon, this cryogenic experimental device weighed 74 metric tons and occupied a warehouse. Yield was 10.4 mt, which was 60% fission.[13]
The TX-16 was a weaponized version of this device: it weighed about 18 metric tons, was 7.56 meters long and had a yield of about 7.5 mt. Part of the weight reduction was accomplished by using equipment in the B-36 to top off the liquid hydrogen before delivery. About 5 "emergency capability" units designated EC16 were built in March 1954. All were retired the following month, however, as solid-fueled thermonuclear weapon prototypes were successfully tested in the Pacific. After the cancellation of the Mk-16, no other liquid-fueled thermonuclear weapons were ever built.[12, 14]
Conventional solid-fueled thermonuclear weapons used lithium-deuteride as fusion fuel. The first such weapon was the EC14; it weighed 13,133 kg and was 5.64 meters long. These "emergency capability" weapons actually preceded the EC16 into the stockpile, with 5 units built in February 1954, making the EC14 the first operational multistage thermonuclear weapon.[11] The design was tested in shot Castle Union on 26 April 1954, producing a yield of 6.9 mt.[5] All were retired in October 1954.[11] These early thermonuclear weapons were carried by specially modified B-36 bombers; the limited number of such converted bombers available in 1954 operated from Kirtland AFB in New Mexico.[12]
Mass-produced multi-megaton weapons
Four high-yield thermonuclear weapons had been rushed into the stockpile in 1954: the EC14, EC16, EC17/Mk-17, and EC24/Mk-24. In the late 1950s, three multimegaton weapons of more robust design were mass produced: the B21, B27, and B36.
The B21 weighed about 7,000 kg and was produced in both clean and dirty versions;[3, 15] a clean version was tested in shot Redwing Navajo on 11 July 1956 at a yield of 4.5 mt.[5] From December 1955 to July 1956 about 275 units were produced. They were all converted to B36-Y1 weapons from June to November 1957.[15]
The B27 weighed 1,430 kg and had a yield of about 5 mt. About 700 were produced between November 1958 and June 1959. All were retired between November 1962 and July 1964.[86]
The 7,900 kg B36 NGB was also produced in a dirty version (B36-Y1) and clean version (B36-Y2). The B36-Y1 had a yield of about 9.5 mt, while that of the B36-Y2 was 6 mt; most of the 940 units built were probably the high yield, dirty version.[16, 17]
The Titan II carried the highest yield missile warhead ever deployed by the United States. This was the W53 warhead with a 9-megaton yield, which could be delivered by the Titan II to a range of 15,000 km.[18] About 60 W53 warheads were built from December 1962 to December 1963.[19]
The first Titan II was placed on alert in April 1963 in Arizona. The first squadron of 9 was operational in June 1963, and full operational capability was attained with 54 deployed in December 1963: 18 near Davis-Monthan AFB in Arizona, 18 near Little Rock AFB in Arkansas, and 18 near McConnell AFB in Kansas.[20, 21, 22] A guidance upgrade was conducted to improve the accuracy of operational Titan IIs from February 1978 to December 1979.[18, 22] On 19 September 1980 leaking fuel exploded in a Titan II silo in Arkansas, killing one and injuring 27. This silo was never returned to service; the same is apparently true of a silo in Kansas damaged by a fuel leak on 24 August 1978.[23, 24]
Retirement of the remaining 52 Titan IIs began in September 1982.[24] The last one was removed from alert in May 1987.[25] Disassembly of W53 warheads had begun in October 1969[19] and was probably completed by 1988.
In January 1963 the U.S. began development of a two-layered anti-ballistic missile system which would eventually be named Safeguard, with the two ABMs being Spartan and Sprint. The first layer, the Spartan missile, was an exo-atmospheric ABM using a high-yield thermonuclear warhead (the W71) to intercept incoming warheads outside the atmosphere. The second was Sprint, an endo-atmospheric high-acceleration ABM using a low-yield warhead to intercept surviving warheads within the atmosphere.[26]
The W71's yield was too large for underground testing at the Nevada Test Site, so Amchitka Island in the Alaskan Aleutians was selected as a site. To evaluate concerns over this site, a test of 1.2 megatons was conducted at Amchitka on 2 October 1969 (Milrow). Political opposition to the W71 test (and the Safeguard ABM system in general) included an appeal to the U.S. Supreme Court attempting to block the test on the scheduled day; the Court rejected the appeal 4-3, allowing the test to procede.[27] On 6 November 1971 the Spartan's warhead, the W71, was tested at full yield in shot Cannikin of Operation Grommet. At the bottom of a 1.76 km-deep shaft,[27] the warhead's yield was reported as "approximately" 5 mt[26] or "less than 5 megatons"[27], estimated here as about 4.8 megatons.
The first W71 units were completed in July 1974, and full production ran from October 1974 to July 1975 [26] by which time 39 warheads had been built.[28] The W71 warhead was "tailored": using a layer of gold around the thermonuclear secondary, the output of x-rays was maximized to achieve a more efficient kill of targeted warheads.[26]
The SALT I treaty, signed 26 May 1972, limited the U.S. and U.S.S.R. each to a pair of 100-missile ABM sites; an additional protocol signed 3 July 1974 reduced this to one such site each. The U.S. selected a site near Grand Forks AFB in North Dakota for the Safeguard site, named the Stanley R. Mickelsen Safeguard Complex,[29] which would provide limited protection to the Grand Forks AFB Minuteman ICBM field.
The first ABMs were emplaced at Grand Forks in late 1974. The first ABMs were placed on alert in April 1975, with 8 Spartans and 28 Sprints operational. The full complement of 30 Spartans and 70 Sprints became operational on 1 October 1975, with all 30 Spartans at the MSR site near Nekoma, North Dakota.[30]
The following day, 2 October 1975, the U.S. House of Representatives voted to shut down the Safeguard site. The U.S. Senate passed a similar measure on 18 November 1975, and that month the Safeguard site was taken off alert. Decommissioning of the site began 10 February 1976.[31, 32, 33]
The Spartan missiles and warheads were retained in inactive storage until the 1990s. The warheads were dismantled in 1995.[34]
The last U.S. high-yield nuclear weapon
(Image: B53 bomb casing at the National Atomic Museum.)
Development of the B53 began in March 1958 as a replacement for the B41.[10] The B53 was carried by the B-47, B-52, and B-58 bombers. It was reportedly produced in two yield versions. The 9-megaton B53-Y1, a "dirty" version, was first produced in August 1962, weighed 4010 kg and was 3.8 meters long. The B53-Y2 was a "clean" version first produced in June 1964; it weighed 3860 kg and was 3.7 meters long.[5, 10] The yield of the Y2 version is unknown, but was probably lower than 9 mt.
When B53 production ended in June 1965, about 340 had been built. Retirement of some early versions began in 1967.[10] When the B41 was retired in 1976, the B53 was left as the only high-yield bomber weapon in the U.S. stockpile.
In 1987 about 25 B53s remained in the active stockpile, plus additional B53s retired and awaiting dismantling. On 5 August 1987 the DOD announced that B53 retirement was being halted, and those retired but still intact units would be returned to the active stockpile.[10] This unusual action likely reflected the B53's then unique capabilities against deeply buried hardened targets in the U.S.S.R.
Thus, at the end of the Cold War, in 1991, there were an estimated 50 B53s remaining in the active stockpile, and their retirement was believed to be emminent.[35, 36] (This figure may not include 28 B53s dismantled between October 1989 and September 1997.[28]) However, in 1995 it emerged that these were being retained pending development of an earth-penetrating warhead.[37] Without the B53, the U.S. would have had no weapon to hold at risk certain superharded, deeply buried targets. The B61-11 was developed as a replacement: with a potential 350-500 kt yield in an earth-penetrating warhead, allowing detonation slightly below the ground surface for better coupling of shock to ground, this was a viable replacement.[38] The B61-11 was deployed from Dec. 1996 to 1997, allowing retirement of the B53.[39]
The B53 was immediately retired from the active stockpile[39]; there were apparently safety concerns with the warhead. Some B53s were disassembled at the Pantex Plant in Texas from 1998 to May 1999, at which time disassemblies were suspended due to safety protocols.[40] Resumption of disassemblies was delayed by adoption of new safety documents and by dedicated efforts at Pantex to complete disassmblies of remaining W56 and W79 warheads from October 2001 to September 2003.[41, 42, 43, 44, 45] In 2002 it was reported that the last B53s, about 35, were to be soon dismantled.[46, 47] DOE documents suggest that some issues still had to be worked out (including transportation from temporary storage at Kirtland Air Force Base in New Mexico[49, 50]), plus disassembly efforts remained concentrated on other warheads (including the W70[51]). Funds for B53 disassembly were included in the FY2004[49] and FY2005[52] budgets and were requested for FY2006[51], but it appears that disassembly efforts remain suspended pending resolution of safety and logistics issues.[48] Plans were then to resume B53 disassemblies after completion of W76 and W80 disassemblies (planned completion in September 2007), along with implementation of the Seamless Safety 21 or SS-21 program for the B53.[54] These SS-21 plans were still being developed as of December 2007,[87] and the first W80 disassembly under SS-21 was not completed until the last week of October 2007.[88] As of August 2008, SS-21 disassemblies of the remaining B53s are scheduled to begin in September 2009.[100] In early 2009, it was reported that the first B53 disassemblies under SS-21 would be delayed until December 2009, which would push back completion of B53 disassemblies until after September 2010 without more resources.[101, 102]
Following removal of the B53 from service, the highest yield U.S. weapon is the variable yield B83, with a maximum yield of 1.2 mt.[53]
Soviet/Russian nuclear warheads with yield over 4.5 megatons
| system (U.S. des.) [warhead] | type | stock entry | IOC | off alert | retired | type | weight (kg) | yield (mt) | no. built |
|---|---|---|---|---|---|---|---|---|---|
| R-16 (SS-7 Mod 1/2/3) | ICBM | Nov 1961 | 1977 | 1950 | ~6 | 0-320 | |||
| R-9A (SS-8) | ICBM | Dec 1964 | 1976 | 1800 | ~5 | 23-46 | |||
| R-36 8K67 Tsiklon (SS-9 Mod 1) | ICBM | Nov 1966 | 1980 | 7000 | 18 | 140-290 | |||
| R-36 8K67 Tsiklon (SS-9 Mod 2) [8F675] | ICBM | 1966 | 1980 | 7000 | 25 | 140-290 | |||
| R-36O 8K69 Tsiklon (SS-9 Mod 3) | FOBS | Aug 1969 | Jan 1983 | 5000 | ~20 | 0-20 | |||
| MR UR-100N (SS-17 Mod 2) | ICBM | 1977 | 1984 | 3500 | ~5 | 10-30 | |||
| R-36M (SS-18 Mod 1) [15B86] | ICBM | Dec 1974 | ~1978 | 7500 | 24 | 20-60 | |||
| R-36MUTTKh (SS-18 Mod 3) | ICBM | 1976 | 1990 | 7300 | 20 | 20-60 | |||
| R-36M2 Voevoda (SS-18 Mod 6) | ICBM | Aug 1990 | 9000 | 20 | 20 | ||||
| UR-100NU (SS-19 Mod 2) | ICBM | 1977 | 3500 | ~5 | 60 | ||||
| RDS-220 ("Tsar Bomba") | NGB | 27000 | ~150 | 0-5 | |||||
| NGB | 50 | 0-20 | |||||||
| NGB | ~20 | 0-120 | |||||||
| NGB | ~5000? | ~5 | ? |
The largest Soviet nuclear weapon
The largest nuclear weapon ever developed by any nuclear power was the Soviet RDS-220,[62] also nicknamed "Big Ivan", "Vanya" or "Tsar Bomba" (King of Bombs). It was a three-stage weapon weighing 24.8 metric tons and was 8 meters long. Its 2-meter diameter required a specially modified version of the Tu-95 Bear bomber for delivery. The single such Tu-95V carried the RDS-220 partially protruding from the bomb bay.[63, 64] The U.S.S.R. tested this design in an airdrop over Novaya Zemlya on 30 October 1961 at a yield of about 58 megatons.[65, 89, 90] However, this was a reduced yield "clean" version: the uranium sleeve on the tertiary stage was replaced with lead, and the fission yield was only 3% of the total yield.[63] The full yield version had a yield variously reported as 100 mt [64] or 150 mt [62]. About 80% of the fallout from the "Tsar Bomba" test was deposited as global fallout.[67]
The yield of the 30 October 1961 test remains the subject of some debate. Best estimate here is that the actual yield was 57-58 mt, based on the following:
Another device tested the following year had a nominal yield of 50 mt. Tested at a reduced yield of 24.2 mt on 24 December 1962 at Novaya Zemlya, it was designed at Chelyabinsk-70 (as opposed to Arzamas-16 for the RDS-220)[66].
Whether either of these weapons was operational is unknown. The RDS-220 was probably never operational: only the single specially modified Tu-95V could carry it, and when doing so it would have been particularly vulnerable to anti-aircraft action. The 50-mt Chelyabinsk-70 device might have weighed 10-15 metric tons, based on comparison to other Soviet warheads of the time. Thus it was probably deliverable by unmodified Tu-95M Bear bombers, which could carry 15 metric tons of payload (albeit to a reduced range).[68] Any operational deployment was probably only for a short time since bomber forces were converting to cruise missiles, but the weapons could have remained in the stockpile as late as the 1980s, given the apparent slow pace of Soviet warhead disassembly.
The Soviets briefly considered developing an ICBM capable of carrying the 150-mt RDS-220 warhead or a similarly large warhead. Of several proposed missiles, only the UR-500 reached the flight stage, by which time any nuclear-armed version was abandoned in favor of using the UR-500 exclusively as a space launch vehicle.[69]
The first Soviet ICBM was the R-7/R-7A, known as the SS-6 Sapwood in the West. Six of these missiles were deployed from 1960 to 1967, with warheads of about 4 mt yield (yield variously reported as 3-5 mt).[93]
Deployment of the R-7 was limited, since the superior R-9A and R-16 ICBMs were deployed a short time later. The R-16, or SS-7 Saddler, was deployed in several versions and with two types of warhead, 3 mt yield or 6 mt yield. The first R-16s were operational 1 November 1961, and by the end of 1965 a total of 186 to 202 missiles were deployed. Retirement began in 1967, and the last R-16 was withdrawn in 1977.[94, 95]
The R-9A, or SS-8 Sasin in the West, carried a 5-mt warhead. It was deployed 14 December 1964 with full deployment of 23-26 by 1966; all were retired by 1976.[94, 95]
The R-36 heavy ICBM, known in the West as the SS-9 Scarp, was deployed in four versions. Two versions of the R-36 carried single warheads: the SS-9 Mod 1 carried a warhead of 10 mt (some sources report 5 mt), and the SS-9 Mod 2 carried the 8F675 warhead with a yield of 25 mt (some sources report 18 mt). The R-36O version (Western designation SS-9 Mod 3) was a fractional-orbit bombardment system (FOBS). It would launch a single 5-mt warhead into low-Earth orbit, southbound from the USSR. Once orbiting over the United States, the warhead would deorbit and strike its target. The system was intended to bypass U.S. early-warning radars. The final version, the R-36P (Western designation SS-9 Mod 4) carried 3 warheads, not independently targetable. Each warhead had a yield between 2 and 5 mt.[70, 71]
The R-36 went on alert on 9 November 1966, and 268 of all four versions were deployed in underground silos. All were retired by 1978 except for some R-36O versions. The R-36O FOBS version, which went on alert 25 August 1969, was retained in small numbers until January 1983, when the SALT II treaty was completed and barred their deployment.[70, 71]
The R-36M, R-36MUTTKh, and R-36M2 heavy ICBMs
The heavy ICBM known in the West as the SS-18 Satan actually includes three related missiles--the R-36M, the R-36MUTTKh, and the R-36M2--with a variety of warhead loadings in each case. Deployed in both MIRVed and single-warhead versions, the single warhead variants carried the largest missile warheads ever deployed.[72, 73]
The R-36M was developed as a replacement for the R-36. Flight tests were conducted from October 1972 to October 1975 on three variants. The 15B86 single warhead version, with a 24-mt yield, was the first version deployed; this was known in the West as the SS-18 Mod 1. These became operational in December 1974 in converted R-36 silos at Dombarovksy. Most R-36Ms were deployed with 15F143 MIRV warheads--eight warheads each--although a ten-warhead 15F143U version also existed. The MIRVed version (Western designation SS-18 Mod 2) became operational in November 1975. A version carrying terminally-guided 15F678 warheads (MaRVs) was tested from July 1978 to August 1980 but never deployed.[72, 73]
The follow-on R-36MUTTKh was flight tested in a MIRVed variant from October 1977 to November 1979, known in the West as the SS-18 Mod 4.[72, 73] The 15F183 warhead section generally carried 10 warheads, although at least one flight test carried 14 warheads.[74] Some R-36MUTTHk ICBMs carried the 15B86 single warhead at 24 mt (Western designation SS-18 Mod 3), now with improved accuracy over the R-36M. In September 1979 the first three R-36MUTTKh regiments became operational; they had replaced all R-36 missiles by 1980, all R-36M missiles by 1982 or 1983, and reached full deployment in 308 silos by 1983.[72, 73]
Another follow-on, the R-36M2 Voyevoda ("commander" in English), was flight tested from March 1986 to September 1989. The MIRVed variant (SS-18 Mod 5), with ten 15F173 warheads, became operational in December 1988. A single-warhead version (SS-18 Mod 6), with the 15F175 warhead providing a 20-mt yield, was deployed in small numbers begining in August 1990.[72, 73] The single-warhead R-36M2 is the highest yield nuclear weapon currently deployed by any nation.
The UR-100N and MR UR-100N ICBMs
The largest PRC nuclear weapon
The People's Republic of China has deployed a warhead estimated at 5 megatons on the Dong Feng 5 ICBM (U.S. designation CSS-4). The DF-5 can carry a 3,000-kg warhead to a range of 12,000, while the improved Dong Feng 5A can carry 3,200 kg to a range of 13,000 km.[78] The warhead is probably a high yield version of the design(s) used in the PRC's thermonuclear tests of 1968, 1970, and 1976 (given the limited number of Chinese nuclear tests, an independent warhead design is unlikely).[76]
Estimated deployments of DF-5s are highly uncertain. The first two DF-5 missiles were deployed in silos in 1981,[78] and the force remained at 2 through at least 1984.[79] Estimated numbers deployed were 18 in June 2000, 20 in 2003,[76] and 24 in 2005, although reports vary. From about 1990 to 2000, deployed DF-5s were replaced with improved DF-5As.[75, 77] Reportedly the DF-5 force is currently organized into three missile brigades. The 803rd brigade in Hunan province was established in 1984 and converted to DF-5A missiles by the mid-1990s. The 804th brigade in western Henan province was established in the late 1980s, converted to DF-5A missiles by 2000, and may include missiles based in tunnels. The 818th brigade in Hunan province was established in 1996 and was likely initially equipped with DF-5A missiles.[77]
© 2003-2008, 2009 by Wm. Robert Johnston.
Last modified 6 April 2009.
Return to Home. Return to Nuclear Weapons.