Taiwan's Air and Missile Defence. Part 1: Tien Kung-1 and Tien Kung-2

Taiwan’s Conventional Defence Series: Introduction

A major armed conflict across the Taiwan Strait would cause significant disruptions to the global economy and have serious geopolitical consequences. Despite persistent calls for Taiwan to enhance its asymmetrical warfare capabilities, information on Taiwan’s defence capabilities has often been outdated and incomplete. In addition, Taiwan’s own conventional deterrence is frequently overlooked in discussions of its security, particularly in the broader context of China-US relations.

This series aims to provide a clearer understanding of Taiwan’s defence capabilities and contribute to the discourse on defence and the wider geopolitical issues surrounding Taiwan. It begins by exploring Taiwan's core defence capabilities, such as air defence, sea control, counter-strike and C4ISR (Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance). The series will then examine the development and outlook for Taiwan’s main military branches, followed by discussions on other relevant topics, including military exercises, defence spending, recruitment, and arms development and procurement.

Long-range Air and Ballistic Missile Defence

The Beginning: Tien Kung-1 and Tien Kung-2

In any high-intensity cross-Strait conflict, a wide range of land-attack munitions would likely be employed to target Taiwan’s critical locations and military assets. These munitions primarily include:

• Theatre ballistic missiles and hypersonic missiles[1]
• Long-range guided rockets fired by multiple rocket launchers
• Subsonic, supersonic or hypersonic land-attack cruise missiles[2]
• Guided bombs and other air-dropped precision weapons
• Loitering munitions and suicide drones

From a cost-effectiveness perspective, long-range surface-to-air missiles (SAMs) are best suited for engaging high-value targets such as manned aircraft, medium and large drones, ballistic missiles, and land-attack cruise missiles. This section will focus on the development and deployment of Taiwan’s land-based long-range air and theatre ballistic missile defence systems, which are currently managed by the Air Force Air Defense and Missile Command. Other key air-defence components, including Taiwan’s C4ISR, early warning radar systems, air force fleet, and shipborne air and missile defence systems, will be discussed in future sections.

Tien Kung-1 and Tien Kung-2

Taiwan’s domestic surface-to-air missile (SAM) development began with the Tien Kung-1 (天弓, meaning Sky Bow). Since its official deployment in 1993, the Tien Kung-1 has proven to be reliable and remains in active service today. The Tien Kung-2 missile, an incremental advancement based on the Tien Kung-1, is currently undergoing refurbishment and being integrated into more capable domestic SAM systems. Although they are no longer Taiwan’s most advanced SAMs, both the Tien Kung-1 and Tien Kung-2 still remain relevant to Taiwan’s long-range air defence.

Tien Kung-1 Missile

In the late 1970s, Taiwan’s military was unable to procure advanced foreign long-range surface-to-air missiles (SAMs) to replace its ageing US Nike Hercules SAMs.[3] Under this circumstance, the development of the Tien Kung-1 SAM was initiated in the early 1980s. After exploring several different designs, the National Chung-Shan Institute of Science and Technology (NCSIST) finalised the Tien Kung-1’s configuration, opting for a wingless body with four control fins at the rear (Figure 1).

Figure 1. Left: Early Tien Kung-1 design, with fixed wings in the middle and control surfaces at the rear, and powered by a ramjet engine. Middle: Tien Kung-1 prototype, powered by a solid motor and steered by control surfaces attached to four large tail wings reminiscent of the US HAWK missile. Right: Final Tien Kung-1 layout is similar to that of the US Patriot PAC-1/2 missile. Images: Weapon (Top left), CTS (Bottom left), China Times (middle), Taiwan MND (right).

A Tien Kung-1 missile weighs 870 kg,[4] has an effective range between 5 km to 80 km, and an effective interception altitude ranging from 30 m to 23 km (Figure 2). The missile is capable of engaging both manned and unmanned aircraft, as well as cruise missiles. According to the NCSIST, it also has good ECCM (electronic counter countermeasures) capabilities.

Figure 2. The commonly cited maximum range of the Tien Kung-1 is 100 km. However, according to a presentation displayed to former President Tsai Ing-wen, Tien Kung-1’s effective range is between 5 and 80 km. Similarly, to present a conservative estimate, this article will use 160 km instead of the commonly claimed 200 km as the maximum effective range of Tien Kung-2/3. Image: Presidential Office

Guidance

Like most modern long-range SAMs, the Tien Kung-1 relies on an autopilot for mid-course flight and adjusts its trajectory based on correction commands from the engagement radar, which continuously tracks the movement of its targets.

Although the Tien Kung-1 is similar in size and appearance to the US Patriot PAC-1/2 missiles, its guidance system differs from that of the Patriot. Specifically, during the terminal phase of flight, the Tien Kung-1 uses semi-active radar homing, while the Patriot PAC-1/2 relies on track-via-missile (TVM) guidance. Under the Tien Kung-1’s semi-active radar homing guidance, the missile uses its own computing power to calculate its flight path until impact. In contrast, in the TVM mode, this calculation is performed by a ground-based or shipborne engagement radar, which directs the missile toward the target (Figure 3).

Figure 3. In the TVM guidance mode, the engagement radar continuously tracks and "illuminates" the target (Step 1). The missile receives the radar signals reflected from the target (Step 2) and relays these signals back to the engagement radar (Step 3). The engagement radar then processes the data to calculate the optimal interception path and sends steering commands back to the missile (Step 4). In contrast, under semi-active radar homing guidance, Steps 1 and 2 are the same, but the missile processes the reflected signals itself and generates its own steering commands for interception. Image: Militarnyi

Without onboard guidance computers, TVM guidance theoretically simplifies each missile, making it cheaper to produce. However, with advancements in microelectronics, semi-active radar homing and active radar homing (where the missile has its own radar seeker) have become more popular among mid- to long-range SAM systems. In the mid-1980s, the NCSIST also experimented with a Tien Kung-1 prototype missile equipped with an infrared (IR) seeker. The IR seeker version never went into batch production.

Engagement radar

Although the Tien Kung-1 was Taiwan’s first indigenous SAM system, the NCSIST decided that the Tien Kung programme must incorporate a passive electronically scanned array (PESA) engagement radar,[5] which offered the best performance at that time. To achieve this ambitious goal, the institute sought technology transfer from RCA (Radio Corporation of America) in 1983. However, the US only agreed to transfer phase shifter technologies that were one-generation behind[6] the most advanced US systems. As a result, the Tien Kung’s Chang Bai PESA engagement radar has cumbersome dimensions, limiting its deployment flexibility (Figure 4).

Figure 4.The Tien Kung-1’s radar suite consists of a Chang Bai PESA engagement radar and two separate target illumination radars. Although the radar prototypes were initially mounted on trailers, both the Chang Bai and its illumination radars were eventually deployed at fixed sites. Images: Youtube (top left and top right), sina (bottom left), sina (bottom right)

The Chang Bai radars have a maximum detection range of over 400 km and are able to detect and track multiple targets. They have reportedly performed well since their induction in 1993, and allegedly were able to track ballistic missiles fired by the People’s Liberation Army during the 1996 Taiwan Strait Crisis.

Tien Kung-2 missile

The NCSIST initiated the development of Tien Kung-2 in the late 1980s. The missile was first designed as a Tien Kung-1 missile on top of a solid-propellant booster. This early design soon gave way to an improved single stage rocket with a slightly enlarged solid motor and a lightweight rocket body (Figure 5).[7] The new design increased the Tien Kung-2’s maximum range to some 160 km (Figure 2). The batch production of the Tien Kung-2 started in 1997, and it publicly participated in a live-fire drill for the first time in 2002.

Figure 5. Launch of a Tien Kung-2 missile. Image: CETN

Guidance

The most significant improvement made to the Tien Kung-2 was the adoption of an active radar seeker, which eliminated the need for radar illumination from the ground during the missile’s terminal flight phase, and further enhanced multi-target engagement capabilities of the Tien Kung system.[8] During the mid-course flight, Tien Kung-2 missile relies on an autopilot and changes its flight path via correction commands from the Chang Bai engagement radar.

Deployment of Tien Kung-1 and Tien Kung-2

Due to the cumbersome dimensions of the Chang Bai engagement radar, the Tien Kung-1/2 systems were eventually deployed at fixed sites. The Tien Kung-1 missiles have mainly been launched from mobile four-canister launchers. However, as the weight of the Tien Kung-2 missile increased from 870 kg to over 1100 kg,[9] Tien Kung-2 missiles had been launched from silo-based vertical launch canisters (Figure 6).[10]

Figure 6. Simultaneous launch of two Tien Kung-2 and one Tien Kung-1 missiles. Image: NCSIST

The first Tien Kung-1/2 SAM site was established in 1993. By 1996, Tien Kung replaced the last US Nike Hercules SAM battery in Taiwan.[11] A Tien Kung-1/2 SAM site consists of a fortified fire control area accommodating the Chang Bai radar installations (Figure 7) and a missile launch area (Figure 8). The two areas are typically around 2 km apart.[12]

Figure 7. Typical fire control area of fixed Tien Kung SAM sites. As the two illumination radars are only required to “illuminate” the targets during the missiles’ terminal phase of flight, the Tien Kung-1 system could engage multiple targets simultaneously. Image: Google Earth, NCSIST (Inset left), Liberty Times (Inset right)

Figure 8. Typical launch area of fixed Tien Kung SAM sites. The Tien Kung-2 missiles are equipped with active radar seekers, eliminating the need for radar illumination from the ground during the terminal flight phase. Image: Google Earth, CTS (Inset left), MNA (Inset right)

By the late 1990s or early 2000s, a total of six fixed Tien Kung-1/2 sites became operational on the main island, the Penghu archipelago, and the offshore Matsu archipelago. Each Chang Bai radar scanned the airspace within a fixed 120-degree field of view, creating a "SAM wall" facing the west (Figure 9).[13]

Figure 9. Approximate missile coverage of fixed Tien Kung SAM sites. Note that in order to offer a conservative estimate, the coverage is drawn with a maximum effective range of around 160 km (Also see Figure 2). Image: Google Earth

In five of the six fixed Tien Kung SAM sites, there are 20 four-canister Tien Kung-2 vertical launch silos and two four-canister Tien Kung-1 mobile launchers, providing a maximum total of 88 launch-ready missiles per site. This number is significantly higher than that of a mobile Patriot PAC-2 or Tien Kung-3 battery, which typically have 32 launch-ready missiles from eight mobile launchers. Although some silos may have been left empty as decoys, two points suggest that all silos were more likely operational:

• Reloading machines were deployed to the fixed Tien Kung SAM sites around the year 2000, shortening the reload time from 65 minutes to 25 minutes per missile. Since it is counterintuitive to leave some silos empty while expending additional time and effort to reload operational ones, it is more reasonable to assume that all Tien Kung-2 silos were fully operational.
• Constructing empty silos as decoys makes little sense when the fixed Chang Bai radars are far more valuable and vulnerable targets.

The only fixed Tien Kung site with fewer missiles is the one at Dongyin, Matsu archipelago. Possibly due to the site’s proximity to Mainland China (approximately 60 km from the Chinese coastline) and its limited space, only 32 silo-based Tien Kung-2 missiles are deployed. The role of these strategically located offshore islands during a possible cross-Strait conflict will be discussed in future sections.

Overall, the six fixed Tien Kung sites have approximately 432 launch-ready Tien Kung-2 missiles and 40 launch-ready Tien Kung-1 missiles, though the total number of Tien Kung-1/2 missiles remains unknown. However, due to the vulnerability of fixed Chang Bai engagement radars against evolving ballistic missile threats, the Taiwan military reportedly did not expect the fixed Tien Kung SAM sites to survive the first day of a major-cross Strait war during a 2008 table top exercise. Thus, the number of reloads may be significantly lower than the number of launch-ready missiles.

To address the survivability issues of the Tien Kung-1/2 systems and enhance Taiwan’s protection against ballistic missiles, the NCSIST started to develop the mobile Tien Kung-3 long-range SAM and ATBM (anti-tactical ballistic missile) system in 1996. Since at least 2017, Tien Kung-2 missiles have been refurbished and integrated into mobile Tien Kung-3 batteries.[14] This integration and the fate of the six fixed Tien Kung SAM sites will be discussed later.

Next article: In parallel to the deployment of the Tien Kung-1/2, Taiwan was also in talks with the US to purchase the Patriot PAC-2 system. The first PAC-2 battery arrived in Taiwan in 1997. The deployment of the PAC-2 and PAC-3 systems will be discussed in the next chapter.

Note: "China" and "Taiwan" are used to refer to the two political entities across the Taiwan Strait. The author uses "Taiwan" with the recognition that People’s Republic of China (PRC) and the Republic of China (ROC, or Taiwan) have two different official positions regarding the status of Taiwan: China views Taiwan as an inalienable part of China, while Taiwan regards itself as a sovereign and independent state.