China DF-31/-31A (CSS-9)

DF-31 (left), DF-31A (right) (Jane's Strategic Weapon Systems)
Basing:Road/rail-mobile
Length:13.0 or 16.0 m
Diameter:2.0 m (1st/2nd stages), 1.5 m (3rd stage)
Launch Weight:42,000 kg
Payload:Single warhead or 3-4 MIRV; 1,050-1,750 kg
Warhead:Nuclear 1 MT or 3-4 MIRV at 20/90/150 kT each
Propulsion:Three-stage solid propellant
Range:8,000-11,700 km
In Service:1999

The DF-31 (CSS-9) is an intercontinental-range, road/rail-mobile, three-stage solid propellant ballistic missile. Development on the missile began in 1970 alongside the missile’s submarine based counterpart, the JL-2. Initially the missile was given the Chinese designator DF-23, but following changes in the program’s requirements, the missile was re-designated DF-31 in the late 1990s. The missile is probably intended to replace the older DF-4 (CSS-3), as its solid-propellant base gives it considerable transportation and launch-time advantages over the older missile. 1

The DF-31 is believed to have a length of 13.0 m, a diameter of 2.25 m, and a launch weight of 42,000 kg. Conflicting reports have placed the maximum range of this missile between 8,000 and 11,700 km. 2 The warhead assembly is expected to have a payload of 1,050 to 1,750 kg with a single 1 MT nuclear warhead, or three to four MIRV units with varying possible yields of 20, 90, or 150 kT and penetration aids. The possibility of these MIRV units is based upon eleven different tests on 20 kT to 150 kT warheads performed by China between 1983 and 1996. 3 Other sources suggest that, while the missile will likely employ penetration aids and defense deterrence measures, it will not carry MIRVs. 4 The missile probably employs a variety of navigation aids, including stellar and GPS systems. While accuracy is expected to be around 300 m CEP, several reports have suggested that a Silo-launched missile would have an accuracy of 100 m CEP and a TEL-launched missile would have an accuracy of 150 m CEP. 5

The PRC also developed an improved version of the DF-31 called the DF-31A. Production presumably began in the late-to-mid 1990s, or latter stages of the original missile’s development. This version uses a significantly longer third-stage motor to bring the missile to a total length of 18.4m and a maximum range beyond 10,000 km. Some reports place the range of the DF-31A between 10,000 and 14,000 km – probably based on payload – while other reports, including official Department of Defense reports, suggest that the range is above 11,200 km. The additional range is very significant because it brings the entire Continental-US within missile range. Compared to its predecessor, this missile has the same diameter in its first and second motor stages, while the lengthened third stage is narrower at 1.5 m in diameter. The overall launch weight is believed to be 63,000 kg. The missile may carry the same or similar warheads to its predecessor, and three to four MIRV units are likely. 6

The DF-31/-31A program is thought to have performed 11 different flights tests on the missile. One source suggests that the August 1999 test was the first comprehensive test of the missile containing a dummy warhead. This same source notes that this August 1999 test was not successful, neither were the two subsequent tests in 2000. 7 The September 2006 flight tested the missile over a distance of 2,500 km and appears to have been successful. The DF-31 became operational in 1999, and the DF-31A likely entered into service shorty afterwards. 8 The 2010 version of the Department of Defense report suggests that, as of August 2010, around 30 DF-31 and DF-31A missiles were operational, representing an increase of 5-10 DF-31A missiles since the 2009 report. 9 Operational missiles are believed to be deployed to units within the Second Artillery Corps of the PLA. Perhaps as many as 50 missiles will be assembled and deployed by 2015. 10

  1. Lennox, Duncan. “DF-31 (CSS-9)” Jane’s Strategic Weapon Systems (Offensive Weapons). August 28, 2012. (accessed September 12, 2012).
  2. Ibid; “Annual Report to Congress: Military Power of the People’s Republic of China 2009,” Office of the Secretary of Defense, p. 66, available at http://www.defense.gov/pubs/pdfs/China_Military_Power_Report_2009.pdf, accessed on 22 July 2010.
  3. Lennox, Jane’s Strategic Weapon System.
  4. Hans M. Kristensen, Robert S. Norris, Matthew G. McKinzie, “Chinese Nuclear Forces and U.S. Nuclear War Planning,” The Federation of American Scientists & the Natural Resources Defense Council, November 2006, p. 76.
  5. Lennox, Jane’s Strategic Weapon System.
  6. “Annual Report to Congress…2009,” p. 25, 66.
  7. “DongFeng 31A (CSS-9) Intercontinental Ballistic Missile,” Sinodefence.com, available at http://www.sinodefence.com/strategic/missile/df31.asp, accessed on 22 July 2010.
  8. “Annual Report to Congress…2009,” p. 24.
  9. “Annual Report to Congress: Military and Security Developments Involving the People’s Republic of China 2010,” Office of the Secretary of Defense, p. 34 and 66, available at http://www.defense.gov/pubs/pdfs/2010_CMPR_Final.pdf, accessed on 23 August 2010.
  10. Lennox, Jane’s Strategic Weapon System.
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