Taiwan unveils TK-4 air defence system, surpassing US Patriot in altitude

Taiwan’s National Chung-Shan Institute of Science and Technology (NCSIST) has publicly introduced the Tien Kung IV (TK-4 or Sky Bow IV) surface-to-air missile system, according to Taiwan Defense News Tracker. 

Taiwan arms manufacturer NCSIST has unveiled the TK-4 surface-to-air missile system for the first time at the Taipei Aerospace and Defense Technology Exhibition.

The system is the latest evolution of the Tien Kung family.

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Part of the decade-long Strong Bow program, TK-4 follows TK-1, TK-2, and TK-3 and has completed combat evaluation and limited production verification, paving the way for serial production in 2026. Taiwan plans to acquire 122 launcher pods in a phased schedule through 2028, complementing ongoing investments in U.S.-supplied and domestically developed equipment, Army Recognition writes in its analysis. 

Technically, TK-4 marks a significant step forward. Its two-stage solid rocket motor enables engagement at altitudes up to 70 km—well above the TK-3’s 45 km and the Patriot PAC-3’s 24 km ceiling.

The missile, approximately 7.61 meters long, achieves speeds near Mach 7 and uses a Ka-band seeker and domestic microwave power amplifier. Observers note design similarities with Israel’s Arrow-2 and radar systems akin to Green Pine or AN/TPY-2, emphasizing a higher-tier missile defense role.

Testing has advanced, with live-fire trials in September 2025 confirming the integration of mobile launchers and active phased-array radars. TK-4 represents a continuation of Taiwan’s incremental improvements in altitude, mobility, and radar sophistication across the Tien Kung family, which began with TK-1 in 1986.

The Strong Bow program also envisions longer-term developments: Strong Bow II variants targeting altitudes up to 100 km and potential surface-to-surface missiles, alongside early-stage TK-5 concepts to formalise these higher interception capabilities. 

By Sabina Mammadli