An SM-6 missile launch. Photo: Facebook / Military and Space Electronics

As major militaries flex and field hypersonic missiles in growing numbers, a new great power race is on for effective defenses against the game-changing weapon. For the United States, the Standard Missile-6 (SM-6) is still the cornerstone of its missile defense systems, signaling a glaring vulnerability to fast-maneuvering hypersonics.

First fielded in 2013, the SM-6 is the first of the “Standard” family of missiles that include three-in-one anti-air, anti-surface and sea-based terminal defense capabilities which enable it to intercept ballistic and cruise missiles.

The SM-6 is deployed in three design “Blocks”, with the SM-6 Block I being the initial version deployed with the US Navy’s Aegis-equipped ships, the Block IA which addresses technical glitches involved in the first version, and the latest SM-6 Dual which can knock out ballistic and cruise missile targets.

Reports have suggested the SM-6 has “nascent” capability against hypersonic targets. While the SM-6 can destroy ballistic missiles flying at hypersonic speeds, its effectiveness against maneuvering hypersonic targets is questionable.

Last year, a pair of SM-6 Dual missiles launched from a US Aegis warship failed to intercept a medium-range ballistic missile (MRBM) target. However, the SM-6 Dual was successfully tested in 2017 and 2015, indicating a mixed record against conventional ballistic missile threats.

As ballistic missiles fly at hypersonic speeds during their re-entry phase, they travel in a predictable ballistic arc, which makes it possible to calculate a midcourse point of intercept. However, hitting a hypersonic maneuvering target would be much more difficult.

Currently, US missile defense capabilities face significant political, technical and cost constraints, which could limit their effectiveness against hypersonic threats.

Political sensitivity to the deployment of missile defense systems in US ally countries can leave blind spots that open wider vulnerabilities. Such countries may be concerned about becoming the targets of an attack themselves.

A THAAD interceptor is test-launched in Kodiak, Alaska, on July 11, 2017. Photo: Leah Garton / Missile Defense Agency / Handout via Reuters
A THAAD interceptor is test-launched in Kodiak, Alaska, on July 11, 2017. Photo: Leah Garton / Missile Defense Agency / Handout

This has been seen in the ongoing protests in South Korea over the deployment of the Terminal High Altitude Area Defense (THAAD) missile defense system, which have been ongoing since 2017.

The geographic limitations of missile defense radar mean that not all critical areas can be protected against attack. That’s noted in the fact that NATO’s missile shield could not protect Bulgaria, Greece, Romania and Turkey from a missile attack coming from Iran by midcourse-interception systems based in Poland, necessitating the development of terminal-phase interception capabilities.

The high price per SM-6 Dual missile – estimated at US$5 million per round – would make it extremely costly to deploy potentially enough of the weapon to defeat a saturation attack of hypersonic missiles, which can be equipped with decoys and other countermeasures to fool missile defenses.

Given these cost and capability constraints, it would seem logical to develop alternative means of defeating hypersonic weapons as part of a layered missile defense. One straightforward option is to field hypersonic interceptor missiles.

While the SM-6 Dual has some hypersonic capability, it is widely believed to be marginal. That said, the US Missile Defense Agency (MDA) has awarded Lockheed Martin, Northrop Grumman and Raytheon Missiles and Defense to come up with a Glide Phase Interceptor concept.

In 2020, the MDA reported funding issues with the program and halted development of a hypersonic interceptor, stating that it would look into more feasible near-term solutions. But current US efforts to develop counter-hypersonic defenses rely on upgrading existing missile defensive infrastructure.

Railguns are another possible defense against hypersonic weapons. Instead of using explosive propellants, railguns use electromagnetic energy to shoot projectiles at hypersonic speeds. This substantially brings down the cost of intercept, as railgun projectiles cost significantly less than hypersonic interceptor missiles.

However, the high energy requirements per shot and the challenge of finding electrodes that can withstand the intense heat of multiple firings remain a significant technical challenge.

Lockheed Martin is developing producible tactical airborne laser weapons that complement kinetic defenses to protect warfighters in the air and on the ground. Image: Lockheed Martin

Another option is to develop lasers as a counter-hypersonic defense. Compared to projectile weapons, lasers have the advantage of instantaneous hits, pinpoint accuracy, scalable power requirements, and negligible cost per shot. However, like railguns, lasers have huge energy requirements, weaken over distance and can be adversely affected by weather conditions.

Yet another option is to disrupt hypersonic weapons’ kill chains. Kill chains consist of the necessary things, people and processes involved in launching missiles and guiding them to their targets.

As such, satellites are a key vulnerability in the hypersonic kill chain, as these weapons rely heavily on satellites for targeting, tracking and guidance. The deployment of anti-satellite weapons and capabilities could thus be part of a more holistic capability development plan against the rising threat of hypersonic missiles.