In late 2021, a missile launched above the atmosphere released a device that raced toward its target at hypersonic speed, concluding a successful test of a hypersonic glide vehicle for China. The test temporarily brought the race to develop hypersonic capabilities into the headlines, but it has been well underway for years.

Hypersonic weapons are among the most recent advanced technologies being developed by top militaries globally to maintain strategic advantage. The weapons are advantageous over existing offensive weaponry—including ballistic missiles—because of their speed, maneuverability, and low trajectory. By definition, hypersonic weapons fly at speeds of at least Mach 5, or five times the speed of sound. Some even exceed Mach 20.

The first use of a hypersonic weapon in a combat scenario came recently, when Russia used a hypersonic missile to target an ammunition warehouse in Ukraine. However, the missile did not resemble the most advanced hypersonic weapons under development, and the categories and strategic uses for hypersonic weapons in today’s climate are often poorly understood.

Developing Hypersonic Weapons

Russia’s missile is technically classified as a hypersonic weapon because it reached speeds above Mach 5, but it did so by using traditional rocket boosters. As U.S. Secretary of Defense Lloyd Austin noted after Russia’s use of the weapon in Ukraine, the technology is not a “game changer” on the battlefield. The most advanced hypersonic cruise missiles rely on a scramjet engine. Scramjet engines are designed to use oxygen in the atmosphere for combustion and minimize the amount of time air spends in the engine. Engine models resilient to extreme atmospheric conditions have been difficult to create.

Developing equipment that can survive the high pressure and heat created by speeding through the atmosphere is one of the main engineering challenges, requiring vast spending on research and development. Whereas ballistic missiles outside the atmosphere are not subject to heat and atmospheric pressures throughout their flights, hypersonic weapons travel entirely through much denser air. Their thin, lightweight materials are subject to bending and warping which could alter their aerodynamic properties. Their sensors are also hard-pressed to maintain functionality.

The United States, China, Russia, and others have invested heavily in developing hypersonic weapons, and most fall into one of two categories: hypersonic cruise missiles (HCMs) and hypersonic glide vehicles (HGVs). The main difference is that HGVs do not have an engine, so they are instead released by ballistic missiles near the top of the atmosphere and “glide” towards their target. HGVs are capable of reaching greater speeds and traveling longer distances than HCMs.

The U.S. has been investing in hypersonic weapons for years, including about $15 billion from 2015 to 2024 across 70 programs. It has already run multiple successful hypersonic missile tests, including the HCM Hypersonic Air-breathing Weapon Concept (HAWC) this past March. The U.S. attempted a test of a glide body last October, but the test was unsuccessful due to a rocket failure. However, the United States has made significant progress towards the capability to deploy an HGV, and it continues to focus on research and development efforts. Most U.S. research is focused on offensive weaponry, but some is directed at countering hypersonic weapons.

Strategic Advantages of Hypersonics

China and Russia would theoretically gain several strategic advantages from developing offensive hypersonic weapons. First, their high speed and maneuverability mean they are unlikely to be intercepted by any existing missile defense technologies. This can prove especially beneficial in regional conflicts such as Russia and Ukraine or China and Taiwan. Additionally, HGVs would also offer American adversaries asymmetric advantages in a conflict with the United States. An HGV could approach the United States from the South Pole rather than the North Pole approach vector favored by ballistic missiles to avoid most U.S. missile defense systems. China’s test last year was an HGV, and Russia’s Avanguard is another HGV, albeit never used.

While China, Russia, and other nations may be motivated to develop hypersonic weapons to obtain an asymmetric advantage and the ability to evade superior missile defense systems, the same does not presently apply to the United States. However, assuming that missile defense systems of its adversaries will improve in the coming decades, the United States may hope to develop offensive hypersonic weapons to preclude any potential threat to their critical infrastructure. Although conventional hypersonic weapons—which often rely on kinetic energy upon impact to cause damage— would not be as powerful as nuclear weapons, they would also strengthen the ability of the U.S. to militarily respond without escalating a conventional conflict to a nuclear conflict.

Risks of the Hypersonic Race

The proliferation of hypersonic weapons carries great risks. First, the weapons could be capable of carrying nuclear warheads, making it more difficult for nations to develop missile defenses against nuclear attack. An aggressor would be near certain that their nuclear warhead would evade missile defenses against any target, potentially encouraging first strike. However, this only applies in an asymmetric scenario where a nation is attacking another with a greater missile defense capacity, such as China or Russia attacking the United States. If the United States were conducting a first strike against a nation without strong missile defense systems, they would have near certainty that a traditional ballistic missile attack would be successful. China and Russia may also not need hypersonic weapons to overcome superior missile defense systems because they could use other asymmetric tactics. For example, they could overwhelm a missile defense system with simultaneous attacks to ensure that at least one of them hits its target. Since hypersonic weapons are not the only asymmetric advantage, they may be unlikely to change the probability of a first strike being successful. Furthermore, an attempt at a first strike remains very unlikely because of the catastrophic risk which would ensue for both sides.

Another risk of HGVs is that they may be mistaken for nuclear weapons. HGVs are released from traditional ballistic missiles after launch, often ICBMs. Launches of ICBMs can be misinterpreted as nuclear weapons, even if the missile does not contain a nuclear warhead but an HGV which it intends to deploy near the top of the atmosphere. A false alarm could trigger a response that escalates into a large conflict.

A larger concern may be that hypersonic weapons proliferate to smaller states and rogue actors. Smaller actors are less likely to be able to create an asymmetric advantage against a larger power through simultaneous, overwhelming attacks, so hypersonic weapons may be their best strategy yet. Hypersonic weapons may enable such actors to launch a successful attack against key infrastructure of the United States or another country by circumventing missile defenses through high speeds and maneuverability. Even without nuclear weapons, such an attack could cause catastrophic damage and pose a serious national security concern. Although advanced hypersonic weapons capabilities are still limited to a small number of nations, North Korea and Iran among others have their own programs, and the risk of unintended proliferation increases in the long-run.

The development of defense systems also intensifies the race to develop more offensive weaponry, which the Cold War-era Anti-Ballistic Missile Treaty between the U.S. and USSR sought to address. Such a cycle is likely to persist in the new arms race, with nations developing more mechanisms to overcome increasingly advanced missile defense systems. These include hypersonic weapons, as well as electronic warfare systems such as jamming and spoofing that Russia has recently demonstrated in Ukraine.

Despite the risk of further escalation, the United States should be committed to developing counter-hypersonics for its own defense, especially since the main risk posed to the U.S. by hypersonics may eventually come from non-state actors. The U.S. has already made significant advances in counter-hypersonics and plans to launch two hypersonic-tracking space sensors within the next year. Further advancements in space domain awareness (SDA) and strengthened institutional decision-making for quicker response times would further enhance its capacity.

AUKUS Collaboration

On April 5, the United States, the United Kingdom, and Australia announced plans to collaborate on hypersonic weapons, including both “hypersonics and counter-hypersonics.” The new announcement signals close cooperation and information sharing on hypersonic weapons research in the future. Based on the initial AUKUS agreement last year, which transferred sensitive nuclear-powered submarine technology to Australia, collaboration on hypersonic weapons is likely to include research at the highest levels of security.

The AUKUS announcement further signifies the intentions of the United States, United Kingdom, and Australia to closely collaborate on advanced technologies relevant to national security with high levels of secrecy for at least the next decade. The AUKUS agreement included cooperation on other emerging technologies, including quantum computing and artificial intelligence (AI). Exclusion of China from industrial and scientific advancements of cutting-edge technologies lock the two sides into a race to stay ahead, both for prestige and national security. While this will lead to redundancy in research, slowing down the rate at which new advancements are made in critical areas, competition with adversaries and close collaboration with allies may be the best strategy for the West to promote global security and democratic world order.

The United States has collaborated with Australia on hypersonic weapons programs for over 15 years. This collaboration most recently includes the Southern Cross Integrated Flight Research Experiment (SCIFiRE), which aims to develop a Mach 5 scramjet-powered hypersonic missile. Before that, the two nations collaborated on the Hypersonic International Flight Research Experimentation (HiFIRE) program, which designed a hypersonic glider capable of flying at Mach 8. Australia is a natural host for hypersonic weapons testing programs because the Woomera Test Range in South Australia has one of the top hypersonic testing facilities in the world. Collaboration with Australia on counter-hypersonics also increases the capacity of the U.S. to defend its interests in the Asia-Pacific region, especially through better SDA.

The U.K and Australia have both become increasingly committed to countering China in the past few years, with Australia being particularly alarmed about power dynamics in the Asia-Pacific region. Its collaboration with the United States on advanced technologies signifies its continued support for an American foreign policy of maintaining an assertive presence in the region. The nations’ new defense plans also pay significant attention to space.

Australia has dedicated greater resources to its military and civil space capabilities in recent years. Its latest budget has a new defense spending package worth about $7.4 billion to enhance capabilities in strategic areas, including cyber and space. The space partnership between the United Kingdom and Australia grew closer in 2021 with the UK-Australia Space Bridge, an effort to increase collaboration between their civil space sectors. Australia’s Civil Space Strategy announced the intention to create 20,000 new jobs in the space sector by 2030 and triple the size of the space sector’s GDP contribution.

The United Kingdom has also demonstrated intent to enhance its space capabilities through its Defence Space Strategy, driven by its goal of “Protect and Defend”. The efforts include an investment of about $1.8 billion over the next decade to develop new space capabilities, including strengthening its strong satellite technology industry. A missing priority may be developing a sovereign precision, navigation, and timing (PNT) system after pulling out of the European Space Agency’s (ESA) Galileo program post-Brexit.

Australia has historically spent significantly less on its space programs than leading spacefaring nations. However, it has a deep history of collaborating with both the United States and United Kingdom on space-related matters, extending back to the launch of the UK’s Prospero satellite from Woomera, Australia in the 1970s. Its geographic position in the Southern Hemisphere makes it an important asset for space awareness, both historically and looking forward.