Taiwan's Air and Missile Defence. Part 3: Tien Kung-3 and Tien Kung-4

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Taiwan to enhance its asymmetrical warfare capabilities, information on Taiwan’s defence capabilities has often been outdated and incomplete. Additionally, Taiwan’s 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

Tien Kung-3 and Tien Kung-4

The previous article outlined the procurement and deployment of Taiwan’s US-made Patriot-2/3 surface-to-air missile (SAM) systems. This article moves on to introduce the development and deployment of Taiwan’s current and future domestic long-range SAM systems, the Tien Kung-3 and Tien Kung-4.

1. Tien Kung-3 SAM

The National Chung-Shan Institute of Science and Technology (NCSIST) developed the Tien Kung-3 SAM on the basis of the Tien Kung-2 with a focus on improving survivability and anti-tactical ballistic missile capabilities. The project was initiated in April 1996, shortly after the 1995-1996 Taiwan Strait Crisis. In 2014, the Ministry of National Defence announced that it would spend 2.3 billion USD to acquire a total of 12 Tien Kung-3 batteries, with the original production and procurement period scheduled from 2015 to 2024. Subsequently, the procurement period was extended to 2026 with an additional 290 million USD. The cost of the Tien Kung-3 is significantly lower than Taiwan’s US Patriot systems (5.6 billion USD for nine batteries). Among other factors, high proportion of domestically produced parts (reportedly reaching 97.31%), introduction of new material and technology,^[1] and the integration of existing Tien Kung-2 missiles (over 400 missiles with unknown number of reloads) into the Tien Kung-3 batteries may have contributed to this low procurement cost.

a. Engagement radar

Early Tien Kung SAMs had to be deployed at fixed sites due to the cumbersome dimensions of the Chang Bai engagement radar. The engagement radar of the Tien Kung-3 system was mainly developed to address this shortcoming. Major improvements of the Tien Kung-3’s engagement radar over the Chang Bai are:

●     New type phase shifters were developed to replace the old phase shifters, enabling significant reduction of antenna surface area while maintaining sufficient detection range.^[2]

●     Domestic development and miniaturisation of digital signal processors, a key component that enables the radar to better distinguish different targets and enhance electronic counter-countermeasure (ECCM) capabilities.^[3]

●     Improvement in capabilities to track and lock on low flying targets under heavy sea-clutter.^[4]

Along with other miniaturisation measures, the engagement radar of the Tien Kung-3 could be moved around by a trailer truck (Figure 1). To further improve the survivability of the engagement radar, a radar decoy vehicle was also added to each Tien Kung-3 battery to confuse enemy anti-radar missiles.

Figure 1. Engagement radar of Tien Kung-3 SAM (Left). The radar antenna is folded during transportation (Right). The engagement radar of the Tien Kung-3 has a 120-degree field of view, and achieves a 360-degree coverage by rotating the antenna.

Images: NCSIST (Left), UDN (Right)

b. Tien Kung-3 missile

The Tien Kung-3 missile could be seen as an enhanced version of the Tien Kung-2. Among other improvements, such as using more up-to-date electronics and materials, the Tien Kung-3 adopted a directional fragmentation warhead (Figure 2) and also possibly more energetic propellants^[5] to better engage fast in-coming targets such as tactical ballistic missiles.

Figure 2. A directional fragmentation warhead is designed to direct much of its explosive energy and shrapnels towards its targets (Left). Testing of Tien Kung-3’s active radar seeker against a simulated reentry vehicle of a tactical ballistic missile (Right). Images: Tencent news (Left), NCSIST (Right).

As all the modifications were internal, the Tien Kung-2 and Tien Kung-3 missiles are visually identical. In fact, the NCSIST had used footage of the Tien Kung-2 to pass off as that of Tien Kung-3 in promotional videos. Except for the markings (Figure 3), the only way to distinguish between the two is through observing their launch canisters (Figure 4).

Figure 3. Except for markings on the missile, it is impossible for outsiders to distinguish a Tien Kung-2 round from a Tien Kung-3 round. Image: NCSIST

Figure 4. Difference in structure and installation between the Tien Kung-2 and Tien Kung-3 canisters. Image: etaiwan (Bottom)

The mix ratio of Tien Kung-2 and Tien Kung-3 missiles per battery cannot be confirmed yet (Figure 5). However, according to production capacity disclosed by the Legislative Yuan,^[6] and judging by the number of available Tien Kung-2 missiles,^[7] the number of Tien Kung-3 might eventually reach around 400^[8] to form a roughly 1:1 mix with the Tien Kung-2 missiles. Presumably, the Tien Kung-3 will be mainly responsible for engaging ballistic targets, while the Tien Kung-2 will be used primarily against air-breathing and other slower targets. Official defence budget plan stated that the benefits to upgrade the Tien Kung-2 system and purchase the Tien Kung-3 system include:

• Enhancing long-range air defence in the main island; Enhancing the protection of key locations in the eastern part of the main island.
• Improving capabilities to counter tactical ballistic missiles. 
• Effectively improving survivability of long-range air defence systems.
• Enhancing overall air defence capabilities through integration of command and control interfaces.
• Improving system reliability through the replacement of aging parts.

Figure 5. A whole battery of eight Tien Kung-2/3 launchers seen during a drill at Su'ao navy port in May 2021. Image: Lee Chung Wei

2. Deployment of Tien Kung-3 units

According to the procurement plan, the 12 Tien Kung-3 batteries have replaced Taiwan's US made HAWK short- to mid-range SAM batteries.^[9] In June 2023, the last remaining HAWK battery in Taiwan was decommissioned.^[10]

Using a long-range system to replace the short- to mid-range HAWK (maximum range 40 km, and most effective at 20 km range) may appear disproportional. However, with technological advancement, attack aircraft tend to release stand-off land-attack munitions and disengage well beyond the effective range of short- to mid-range air defense systems. Among these stand-off munitions, the cheapest and most commonly used type is the guided/glide bomb. Once released, these bombs are hard to intercept. However, to achieve a long, stand-off range, these aerial bombs are typically dropped from a sufficiently high altitude, making the attack aircraft vulnerable to long-range SAMs. Thus, the decision to mass produce the Tien Kung-3 caters to the needs for both anti-tactical ballistic missiles and countering other acute aerial threats that are beyond the reach of short- to mid-range SAMs.

The Air Force Air Defense and Missile Command plans to complete the construction of 12 Tien Kung-3 bases by the end of 2026 (Figure 6). According to media reports and construction works spotted in satellite images, these bases are primarily consisted of former Tien Kung-1/2 fixed SAM sites^[11] and former HAWK SAM sites. Prior to the completion of these bases, the Tien Kung-3 units have been deployed at several temporary locations across the main island of Taiwan.

Figure 6. Likely locations of Tien Kung-3 bases and their coverages. Image: Google Earth

While the Tien Kung-2 missiles have been seamlessly integrated into Tien Kung-3 units, the fate of the Tien Kung-1 missiles remains unclear. Presumably, the 40 to 80 Tien Kung-1 missiles could be:

• Retired, considering that the number of Tien Kung-1 missiles is not particularly high.
• Kept along with a few Chang Bai radar sites.^[12] However, constraints in human resources and budget would make this option less likely.
• Eventually be integrated into Tien Kung-3 units,^[13] though existing official documents suggest that this option was not chosen.
• Mated with retired HAWK radars to form mobile air defence units. While this combination was applied by Taiwan in the late 1980s and early 1990s as a stop gap measure,^[14] decrease in performance,^[15] aging equipment and human resource constraints would make this option less likely. However, a “FrankenSAM” option might become attractive during war-time.
• Converted into ground-attack rockets.

3. Chung Kung/Enhanced Tien Kung-3/Tien Kung-4 SAM

The research and development of an enhanced Tien Kung-3 SAM system (also referred to as the Chung Kung, meaning mighty bow) was initiated in 2014, soon after the completion of the development of the Tien Kung-3. The enhanced Tien Kung-3 reportedly passed initial combat evaluations in February 2023. In December 2023, a Legislative Yuan award was given to the director of NCSIST’s system development center for his role in the mass production of the Tien Kung-3 and the development of the enhanced Tien Kung-3. During the awards ceremony, then Premier of the Executive Yuan Chen Chien-jen and then President Tsai Ing-wen stated that:

• The enhanced Tien Kung-3 adopted, for the first time, a combined-attitude control system (Most likely referring to a combination of aerodynamic control surfaces and reaction control systems such as side thrusters), to ensure the missile’s manoeuvrability in a very thin atmosphere at high altitude, examples of this type of control system can be found in the Aster series and the Patriot PAC-3 missiles.
• An active electronically scanned array (AESA) radar (Figure 7) was developed as part of the enhanced Tien Kung-3 system. Combined with domestically written software, the new radar could better predict the interception point against ballistic missiles.
• The enhanced Tien Kung-3 system could effectively counter maneuvering ballistic missiles.

Figure 7. Information on radars displayed in NCSIST exhibition hall. Image: NCSIST/Paul Lee

In March 2024, this AESA radar was seen along with a Tien Kung-3 battery currently deployed at the Taitung air base (Figure 8), suggesting that existing Tien Kung-3 batteries may be integrated with the Tien Kung-4 systems in the future.

Figure 8. A mobile AESA radar spotted at NCSIST Jiupeng test site (Left). A mobile AESA radar temporarily deployed along with a Tien Kung-3 battery at Taitung air base (Right). Images: Taiwan ADIZ (Left), Google Earth (Right).

According to a control list of military items released by the Ministry of National Defense in July 2024, the enhanced Tien Kung-3 was likely internally referred to as the Tien Kung-4. The control list also revealed that the dimension of the Tien Kung-4 launch canister is 7.64 m x 1.1 m x 1.1 m, significantly larger than the dimensions of that of the Tien Kung-3 (5.5 m x 0.8 m x 0.8 m). Judging by the length of its canister, the size of the Tien Kung-4 is roughly comparable to the Russian S-300 SAM (7.2 m to 7.5 m in length). However, available information is insufficient to determine the layout of the enhanced Tien Kung-3/Tien Kung-4, such as whether the missile has one or more rocket stages, or if the missile has an interceptor that separates from the booster after burnout. The enhanced Tien Kung-3/Tien Kung-4 likely has a terminal active radar seeker^[16] but it remains unclear if it has a hit-to-kill vehicle or primarily relies on an explosive warhead to destroy targets.

The enhanced Tien Kung-3/Tien Kung-4 reportedly has an interception altitude of up to 70 km,^[17] while the interception altitude of the Tien Kung-3 and the Patriot PAC-3 MSE stands at approximately 30 km.^[18] A more advanced variant, often referred to as the Chung Kung-2 by local media, could reportedly reach an interception altitude of 100 km, which might roughly put its kinematic performance in the same category with the US Terminal High Altitude Area Defense (THAAD) system.^[19]

Next article: The next article will provide an overview of all long-range SAMs that are currently operated by Taiwan. It will also attempt to assess Taiwan’s overall long-range air defence capabilities vis-à-vis relevant PLA offensive capabilities targeting Taiwan.

Acknowledgement: the author would like to thank Matt (Twitter handle @Lorenzo65278848), a long-time OSINT researcher in the subject matter, for his valuable feedback and review.

---

Tianran Xu is an Analyst for Open Nuclear Network (ONN), a programme of PAX sapiens. Tianran focuses on North East Asian security and missile systems. Tianran uses photo mensuration to measure the size, range and capacity of missiles. He also analyses photos, videos and satellite imagery to understand nuclear and missile programmes. With a background in media and journalism, Tianran is a regular contributor to Chinese and English open source and science publications. Prior to joining ONN, he worked as a journalist, editor and news assistant at both Chinese and foreign news organisations in Beijing. Contact: txu@paxsapiens.org

---

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.

^[1] Reportedly, the NCSIST adopted domestically built gallium arsenide-based high-frequency microwave power amplifiers, instead of traveling-wave tube-based microwave power amplifiers used by the Patriot missiles, significantly reducing the production and maintenance cost.