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On the same day the US and Israel launched air strikes against Iran, a research team led by Liao Longwen with the Northwest Institute of Nuclear Technology published a paper in the Chinese journal Tactical Missile Technology on the ability of US missile defence systems to intercept hypersonic weapons.
The US systems were dangerously outmatched by these threats, the researchers concluded in the paper released on Saturday. “Existing US missile defences can theoretically intercept some hypersonic weapons in their final stage, but high speed, manoeuvrability and stealth make it very difficult,” Liao and his colleagues wrote.
The prediction appeared to be confirmed by footage that surfaced days later, showing Iranian missiles breaching Israeli and American defences over Tel Aviv and other areas, striking high-value military targets with astonishing speed.
On Thursday, Iran’s Islamic Revolutionary Guard Corps announced that during the 17th round of Operation True Promise 4, its hypersonic missiles and attack drones penetrated the US-made THAAD – Terminal High Altitude Area Defence – system, hitting the Israeli Ministry of Defence building and Ben Gurion International Airport near Tel Aviv.
Hypersonic missiles are defined by their high speed, strong manoeuvrability and unpredictable flight paths, enabling them to penetrate conventional air defence systems in moments. The United States has deployed both midcourse and terminal-phase missile defence systems to counter this.
Analysing the strengths and weaknesses of these systems, the team found that for midcourse interception, the US relied on the Ground-Based Midcourse Defence system and the Aegis SM-3 ship-based midcourse defence system. Both interceptors are designed for hit-to-kill engagement.
“However, because the heat generated by high-speed travel through the atmosphere can blind the infrared sensors used to lock onto targets, these interceptor missiles are only effective against targets outside the atmosphere, which is above 100km (62 miles),” the paper said. Terminal-phase defence systems, by contrast, are designed to intercept incoming weapons during the final stage of flight. Also known as “in-atmosphere” defence systems, they include the widely deployed THAAD, Patriot and the Aegis SM-2 and SM-6 interceptors.
THAAD has been deployed at US military bases in Bahrain and Kuwait, as well as in South Korea and Israel. Its interceptor missiles travel at around Mach 9 and are equipped with two propulsion systems – one for maneuvering and one for attitude control – to enable direct-impact interception.
“The system operates at altitudes between 40km and 150km. When hypersonic missiles glide at lower altitudes, they become difficult to intercept, and at higher altitudes, they are vulnerable to decoy interference,” the team said. For threats below 40km, defence responsibilities fall to systems such as the Patriot PAC-3 MSE, as well as ship-based Aegis SM-2 and SM-6 interceptors. Each interceptor typically protects a radius of several tens of kilometres, making it suitable for defending high-value assets like military bases and airports.
However, because interception occurs in the terminal phase, the system’s reaction time is extremely limited, making it difficult to counter highly maneuverable targets. The team also looked at the potential for successful interception by modelling a scenario involving the PAC-3 MSE and the HTV-2 hypersonic vehicle.
“When a wedge-shaped hypersonic glider approaches its target, it can flip and use lift to dive sharply towards the ground,” the paper said. “To intercept it, the PAC-3 MSE must strike with kinetic force. According to guidance theory, the interceptor needs two to three times the target’s lateral acceleration, greater speed and strong lift for last-second adjustments.”
The team calculated the lift factors, a factor measuring terminal correction ability, of both the PAC-3 MSE and the HTV-2, concluding that effective interception is only possible when the HTV-2’s speed is below Mach 6 and at a moderate altitude.
“If the HTV-2 enters its dive phase at initial speeds above Mach 9, it can maintain speeds above Mach 6 throughout the dive, remaining beyond the reach of interceptors,” the paper said.
“Other interceptors such as the Aegis SM-2 and SM-6 travel at around Mach 4, slower than the Patriot PAC-3, and are even less effective in interception scenarios.
“Even if a hit is possible, it may not destroy the weapon. The interceptor might not hit a vital spot, or it may fail to cause enough damage to stop the missile. Hypersonic weapons are designed with damage resistance and redundant power systems, so even a partial hit might not stop them from completing their mission.” The team said that better coordination between space-based early warning systems and ground radar was key to improving land-based defences against hypersonic glide vehicles.
“This would boost accuracy and cut reaction times. One example is the US Missile Defence Agency’s HBTSS satellite system, which aims to use around 200 space-based sensors for detection,” the paper said.
Early last year, the Trump administration proposed the “Golden Dome” defence system, which would use hundreds of low-orbit satellites armed with interceptors, lasers or rail guns to take out missiles shortly after launch. The goal is to enable global early warning and create a layered defence alongside systems like Patriot and THAAD. However, it remains unclear when the system might become operational.
