The Sky Spear (天戟 Tien Chi) short-range ballistic missile (SRBM) is a Taiwanese short-range ballistic missile capable of striking targets on mainland China. Derived from the Sky Bow II (Tien Kung-2) surface-to-air missile, the Tien Chi has a two-stage booster that extends over the single-stage Tien Kung-2. Developed by the Chungshan Institute of Science and Technology (CSIST) in Taiwan, the Tien Chi has a payload of less than 100 kg. As of early 2001, up to 50 Tien Chi missiles were deployed at two sites: Tungyin Island, and an unidentified second location. The Tungyin Island missiles are said to be housed in silos and protected by batteries of Tien Kung-2 SAMs.
Information provided by CSIST to Jane's Missiles and Rockets, revealed that Tien Chi uses a submunition warhead and there is no unitary warhead for this missile. According to this report, Tien Chi was developed by CSIST following test firings of a Tien Kung 2 variant with a 120 km range and a 90 kg HE warhead. The report also credited Tien Chi missile with a range of 300 km and a 500 kg payload. This range is well beyond the reported 200 km maximum range of the Tien Kung II SAM system, but since Tien Chi is used in a tactical surface-to-surface missile role, it would fly a more efficient trajectory with no need for energy-consuming manoeuvres. Guidance is believed to be an integrated INS/GPS system.