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In
July and August 2021, China tested new types of hypersonic weapons that
appear to differ in significant ways from any that have been tested
previously, either by other countries or by China itself. In each test,
China fired a payload into low-Earth orbit, which travelled at least
partially around the globe; it then released a hypersonic glide vehicle
that travelled through the atmosphere to a
target site in Chinese territory. This is very different from how
hypersonic gliders are typically launched, via a short, suborbital
ballistic flight. The glider in the July 2021 test released a missile
during its final approach, which was particularly surprising
to international observers given that this was the first time such
technology has been demonstrated during long-range hypersonic flight.
These tests suggest that the People’s Liberation Army Rocket Force, the
branch of China’s military responsible for land-based
long-range nuclear and conventional missile operations, may be
developing innovative new weapons-delivery systems. It is possible,
however, that they were part of a broader effort by China to develop
intercontinental-range hypersonic weapons, which might not
result in the eventual deployment of an orbital glider. China has not
officially confirmed these tests, and official spokespeople have said
that the tests were related to the development of reusable spacecraft
with civilian applications.
The orbital glider-release system
China’s new weapons demonstrated unprecedented capabilities, but their constituent technologies – including hypersonic glide vehicles, orbital weapon systems, and a possible two-stage-to-orbit concept – are all familiar. A Cold War-era platform – the fractional orbital-bombardment system – is the closest analogue. But given that China’s system may have completed a full orbit of Earth, rather than a partial or ‘fractional’ one, it may be more usefully described as an orbital glider-release system (OGRS). Both types of weapons rely on the use of a large booster rocket to insert payloads into low-Earth orbit.
The only fractional-orbit system ever to become operational, the Soviet Union’s R-36O (RS-SS-9 Mod 3 Scarp), was first successfully tested in January 1967 and was deployed until the early 1980s. (The 1979 SALT II Treaty prohibited these types of weapons.) The primary strategic driver for that programme was concern about US anti-ballistic-missile systems and North Pole-oriented warning radars. The Soviet Union began studying the fractional-orbit concept because it offered a way of penetrating US anti-ballistic-missile systems with an element of surprise. It was constrained, however, by the 1967 Outer Space Treaty, which states that parties must ‘undertake not to place in orbit around the earth any objects carrying nuclear weapons’. The R-36O was designed to insert a nuclear warhead on a ‘bus’ into a fractional orbit. When the bus approached a desired target, it could fire on-board rocket motors to de-orbit the warhead and direct it as needed. Most critically, a fractional-orbit payload could be launched on a South Pole-bound trajectory, bypassing US early-warning and missile-defence systems focused on northerly approaches. At the time, the US stated that it did not consider the launch of nuclear weapons into a fractional orbit a violation of the treaty.
"China’s concerns about US missile defences have been an important spur to its development of hypersonic glide vehicles in general."
China’s July and August payloads may have completed a full orbit of Earth, according to public reporting. The test vehicles did not carry live nuclear weapons, but if they had they would have violated the treaty, which China has signed and ratified. The same system, however, could presumably comply with the treaty terms if nuclear payloads complete only a fractional orbit, given the Soviet precedent. This interpretation could be disputed, however, based on uncertainty about the definition of the term ‘in orbit’. (For example, objects that reach orbital velocity while outside Earth’s atmosphere could be understood to be ‘in orbit’ for treaty purposes.)
China’s concerns about US missile defences have been an important spur to its development of hypersonic glide vehicles in general. As early as 2014, the US Department of Defense observed that China was ‘working on a range of technologies to attempt to counter US and other countries’ ballistic missile defense systems’. In February 2020, General Terrence J. O’Shaughnessy, then-commander of US Northern Command and the North American Aerospace Defence Command, testified to US lawmakers that China was ‘investing heavily to improve the survivability and penetrability of its nuclear forces’ via ‘an intercontinental range hypersonic glide vehicle … designed to fly at high speeds and low altitudes, complicating our ability to provide precise warning’. Because hypersonic gliders manoeuvre aerodynamically within the Earth’s atmosphere, they are impervious to interception by the two existing US missile-defence systems that have shown some real-world capability against traditional intercontinental-range ballistic missiles: the Ground-based Midcourse Defense (GMD) system and the Aegis ballistic-missile-defence system using the Standard Missile 3 Block IIA interceptor. These systems cannot intercept targets inside the Earth’s atmosphere.
Strategic rationale
If China’s OGRS is indeed intended as a strategic nuclear-delivery system, it was probably developed as an additional means of defeating missile defences. The US GMD system, which was developed with limited ballistic-missile threats from North Korea in mind, is designed to intercept incoming ballistic-missile re-entry vehicles in northern latitudes and has no capability against hypersonic gliders. The US currently possesses 40 interceptors based in Alaska and four based in California, and multiple interceptors would be fired at each incoming ballistic missile. But Chinese leaders are concerned that such missile-defence systems create a so-called ‘ragged second-strike problem’, which would arise in a scenario in which a US nuclear (or conventional) first strike destroys most of China’s nuclear arsenal, leaving it with a second-strike capability so small that it could be neutralised by US interceptors. (The plausibility of this scenario is debated.) Chinese leaders may view an OGRS or intercontinental hypersonic-glider capability as a substantial improvement on the country’s current second-strike capabilities and a hedge against future US missile-defence development. For example, the US is attempting to develop the capability to intercept incoming hypersonic weapons during the glide-phase of flight.
While the US claims as a matter of policy that its homeland missile defences are focused on North Korea, the 2019 Missile Defense Review states that the GMD system, when used in a conflict, ‘would defend, to the extent feasible, against a ballistic missile attack upon the US homeland from any source’ (emphasis added). The secondary missile fired during the July 2021 test might be intended to enable China to defeat new US point defences that it might in the future choose to place near strategically important command-and-control nodes or in fixed long-range missile silos. This missile could neutralise related missile-defence installations or radars prior to the glider’s arrival on target.
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