The advent of short, medium and, perhaps, long-range hypersonic weapons with nuclear warheads presages a major change in the strategic balance. Existing air defense systems cannot defeat hypersonic weapons, particularly air defense systems that rely on kinetic hit to kill intercept missiles. 

The United States has to change its missile defenses quickly or face considerable danger. It may have to reinvent the Reagan-era Strategic Defense Initiative.

In the past decade, there has been a shift in air defense intercept missiles from missiles that explode in proximity to a target, releasing lethal fragments made of “hard” materials such as tungsten, depleted uranium and zirconium.

For example, the Sidewinder air-to-air missile features a warhead – type WAU-17/B – that contains 200 titanium rods that tear up an aircraft. Because the modern Sidewinder missile (AIM-9X) is an infra-red heat-seeking missile, most of the time the missile will run up towards the tailpipe of a jet’s engine and explode, although late-type Sidewinders can also engage an enemy from the front or side. 

Many modern air defense systems use fragmentation warheads, such as Patriot and Russian systems such as BUK.

Kinetic kill missiles, or “vehicles,” sometimes called Exo-atmospheric kill vehicles (EKV), are designed to directly intercept an incoming missile generally at high altitudes

Kinetic energy

These missiles, as now used, do not have an explosive component – instead, they use kinetic energy to destroy an enemy ballistic missile, something like the damage that an asteroid could cause impacting earth. To get an idea, look up to the moon and you will see huge craters caused by meteor and asteroid strikes.

Short-range hypersonic missiles are essentially all-in-one kinetic kill vehicles that can be used against land and surface sea targets.

The United States has been developing different kinetic kill vehicles over a period of 30 years, a process that was started under President Ronald Reagan’s Strategic Defense Initiative. 

The kill vehicle was thought to do best at definitively destroying the target and minimizing the effect of a nuclear blast or fallout from a wounded but not killed incoming nuclear missile. A special Congressional Research Service evaluation of kinetic vehicle research, development and testing says kinetic vehicles have a “mixed and ambiguous” result. 

In simple terms, this means that as much as half the time the kill vehicle misses the target. Unlike fragmentation blast warheads, if a kinetic kill vehicle misses its target even by a little bit, the target is unaffected. In a blast fragmentation warhead, if the blast is in the proximity of a target it can still damage or destroy the target.  

In the past few years, new technologies have begun to emerge that make the blast fragmentation warhead more optimal and effective. One technology, developed by the US Company Alliant Techsystems – merged with Orbital and subsequently purchased by Northrop Grumman – developed a new type of reactive fragmentation system (RM) made of a Thermite-like pyrotechnical composition.

Hitting a hypersonic missile

Used in a warhead, it is ignited by a palladium-clad aluminum wire pyrotechnical initiator which explodes the materials as it hits very close to the target. According to some claims, RM type warheads can increase lethality by 500%.

Under current technology the chance of hitting an incoming hypersonic missile is a low probability due to (a) the speed of the hypersonic missile; (b) the altitude of the hypersonic missile, especially low-flying cruise missiles; (c) the reduced time to detect and kill an incoming hypersonic missile and (d) the slower speed of intercept vehicles and (e) the reduction of radar sensor’s effectiveness. 

Because cruise missiles are also maneuverable and hard to pick up in the early phase of their launch, existing air defenses that are designed around, at best, supersonic targets, won’t work against hypersonic ones. The practical import of this is that at present all existing air defense system are rendered ineffective and obsolete against hypersonic vehicles – powered and glide versions.  

Supersonic missiles and aircraft fly at a speed of Mach 1, or 768 mph, 667 knots, or 1,235 km/h, or greater up to Mach 5, 3,636.35 mph, 3333.69 knots or 6,174 km/h. Hypersonic missiles, using scramjet engines or launched from ballistic missiles in a hypersonic glide, can operate well beyond Mach 5 and theoretically up to Mach 20. Mach refers to the sound barrier and Mach numbers are multiples of the sound barrier number.  

Russia is developing hypersonic weapons that use nuclear reactors and can loiter for hours or even days. The 9M730 Burevestnik is the hypersonic nuclear-powered cruise missile that exploded on a barge just outside of the village of Nyonoska, killing five Rosatom scientists and two service personnel. 

NATO calls this new still-developmental missile the SSC-X-9 Skyfall. It is believed the Burevestnik is to be armed with a nuclear warhead and powered by a nuclear-reactor engine after a conventional rocket initially powers the Burevestnik. The actual speed of the missile is not known at present, but some think it will operate in the range of Mach 8 to Mach 9.  

Russia has already developed a hypersonic glide vehicle called Avangard (Objekt 4202, Yu-71 and Yu-74). This vehicle is released from an intercontinental ballistic missile like the new Russian Sarnat ultra heavy ICBM. It can reach speeds of Mach 20, according to reports from Russia.

Should Russia’s work on the nuclear-powered 9M730 prove to be successful – there have been three known failed launches so far, the first at Pankova [Noyaya Zemlya] in November, 2017, the second at Kapustan Yar on January 27, 2019, near Volgograd, formerly Stalingrad, and the August 8 failure at Nyonoska), Russia will possess a new capability that undermines all current air defense systems because it does not have to be launched by an ICBM and does not travel into space.

For the record, it is important to note that the US is considerably behind deploying ballistic missile defense systems. It has a modern system (THAAD) in South Korea, another THAAD system in Guam and one based in Hawaii, a system planned for Japan – both land and sea-based SM-3 Block II-a interceptors, under development – and Japan and Taiwan have Patriot Advanced Capability-3 (PAC-3) systems. 

The US has deployed the SM-3 II-b defense system in Romania (temporarily) and an SM-3 system is expected to become operational in Poland in 2020. The US operates the more capable Ground Base Midcourse Interceptor system (GBI) in Alaska at Fort Greely (44 interceptors) and in California (4 interceptors) at Vandenberg Air Force base.  

GBI was supposed to be upgraded with a new interceptor called the Redesigned Kill Vehicle (RKV). On August 21, in a surprise announcement, the Pentagon canceled all work on the Redesigned Kill Vehicle. Boeing was the prime contractor and Raytheon was the top subcontractor in the program.  

RKV was dropped because of the emergence of hypersonic threats both from Russia and China. Instead, the Pentagon says it will come up with something better to deal with the “advanced threat.”

Arms control environment

The arms control environment has been deteriorating in an accelerated way in the past 20 years. In 2002, the US withdrew from the Anti Ballistic Missile treaty, once thought of as the “cornerstone of strategic stability.”   

On August 2, 2019, the US withdrew from the 1987 Intermediate-Range Nuclear Forces (INF), citing Russian violations. While a New START nuclear weapons treaty was signed in 2011, it will expire in 2021 unless renewed. Given the problems and fragility of relations between Washington and Moscow, it is difficult to determine if the treaty will be renewed.

Meanwhile, China is developing hypersonic weapons and maintains a substantial nuclear arsenal. According to the Bulletin of Atomic Scientists, “China is the only one of five original nuclear-weapon states that is increasing its nuclear arsenal.

According to some estimates, the country could “more than double” the number of warheads on missiles that could threaten the United States by the mid-2020s.” China also is shifting its nuclear arsenal to long-range missiles aimed primarily at the US and US strategic bases and assets. 

Furthermore, China has steadfastly refused to enter into nuclear arms agreements either directly with the United States or with the United States and other nuclear parties, especially Russia. China has also, despite its current positive relations with Russia, been concerned about Russian missiles near its border and has been strengthening its ability to counter them.

A risk too far

From a US perspective, a rising China and an increasingly brittle relationship with Russia is forcing a rethink of America’s offensive and defensive strategy. 

The currently limited missile defense systems deployed by the United States even today is far from adequate to offset growing threats. With the rise in hypersonic cruise missiles and other long and medium-range hypersonic weapons, the US has a growing national security problem on its hands. It can not defend against even tactical non-nuclear hypersonic systems.

Far greater attention to effective ballistic missile defense is urgently needed at both the strategic and tactical levels. Otherwise, the entire range of US defenses is at risk.

While there can be some offset if the United States successfully deploys its own hypersonic cruise missiles, so far at least most of the emphasis is on tactical hypersonic systems that don’t mitigate the strategic threat from either Russia or China.

One avenue that needs urgent emphasis is a new-concept Strategic Defense Initiative. Some of the early warning elements are in place – especially satellite sensors for ICBMs – but need updating. Other components to successfully destroy an incoming hypersonic missile are missing, precisely because cruise missile-based systems don’t require ICBMs and therefore don’t have the overhead viewable signature that older ballistic missile systems were designed to detect using satellites and radars.

Therein lies the challenge for the US Defense Department, which it is starting to grasp. The great risk is that an adversary may think he has such a huge strategic advantage that he can destroy his enemy with minimal losses, and precisely that is a risk too far for the United States.