DF-31A

DF-31 (CSS-9)
Dongfeng-31A after a military parade in 2015
Type	Intercontinental ballistic missile
Place of origin	People's Republic of China
Service history
In service	2006 (DF-31), 2007 (DF-31A), in development (DF-31B)
Used by	Second Artillery Corps
Production history
Manufacturer	Academy of Rocket Motors Technology (ARMT)
Specifications
Weight	42 t (41 long tons; 46 short tons)
Length	13 m (42 ft 8 in)
Diameter	2.25 m (7 ft 5 in)
Warhead	1 Thermonuclear weapon@ 1 Mt with decoys (DF-31 & DF-31A) 3-5 Nuclear @ 20, 90, or 150 kt each with MIRV (DF-31B)
Engine	Solid-fuel rocket
Operational range	7,200–8,000 km (4,500–5,000 mi) (DF-31) 11,200 km (7,000 mi) (DF-31A)
Guidance system	Astro-inertial guidance with BeiDou Navigation Satellite System
Launch platform	Silo, 8 axle TEL

The Dong Feng 31 (simplified Chinese: 东风-31; traditional Chinese: 東風-31; literally: "East Wind-31"; NATO reporting name CSS-9) is a long-range, road-mobile, three stage, Solid-fuel rocket intercontinental ballistic missile (ICBM) in the Dongfeng missile series developed by the People's Republic of China. It is designed to carry a single 1-megaton thermonuclear weapon. It is a land-based variant of the submarine-launched JL-2. It is operated by the Second Artillery Corps (SAC) which, in 2009, was estimated to have under 15 DF-31 missiles and under 15 DF-31A missiles in inventory. It is not known how many missiles of this type the SAC currently has.

The DF-31A is believed to have incorporated many advanced technologies similar to current generation Russian ICBMs, including the use of penetration aids such as decoys or chaff and maneuverable reentry vehicles to complicate its enemy's missile warning and defense system.

The PRC began developing the DF-31 as a second-generation ICBM successor of the DF-4 in January 1985. ARMT (then called the 4th Aerospace Academy) was appointed as the main contractor while the research arm of the Second Artillery Corps provided contributing support. The land-based variant of the JL-2 was originally called the DF-23 but was changed later on to the DF-31 because of a change in operational requirements. In 1999, the missile was first displayed publicly at the National Day Parade. On August 2, 1999, the Chinese state news media reported the successful test of the DF-31. The third test flight of the missile occurred on November 4, 2000; the second test flight had taken place earlier that year. Operational deployment of the missiles reportedly began in 2006. In 2009, US Air Force Intelligence reported that under 15 DF-31 missiles had been deployed.