Navy’s SM-6 Missile Used In Combat: Report

The Pentagon is said to have confirmed for the first time the use of the U.S. Navy’s SM-6 missile in the ongoing campaign against missiles and drones launched by the Iran-backed Houthi militants targeting shipping in the Red Sea and the Gulf of Aden. If the SM-6 was indeed employed, it would be the first known use of this surface-to-air missile in combat. As we have discussed in the past, the SM-6 offers some unique capabilities, including defense against incoming ballistic missiles in the terminal phase of flight, which appears to have been the case on this occasion.

An unnamed U.S. defense official told Fox News that an SM-6 was successfully fired against a Houthi anti-ship ballistic missile (ASBM) in the Gulf of Aden yesterday. The SM-6 — or Standard Missile-6 — was said to be launched by the Arleigh Burke class destroyer USS Carney (DDG-64), a warship that has already seen plenty of action engaging Houthi threats, since the Hamas attack on Israel last October 7 triggered a wider conflict in the region.

While it remains possible, even likely, that the USS Carney and other U.S. Navy warships have employed the SM-6 on previous occasions during the ongoing crisis, the U.S. Department of Defense has not formally acknowledged it. After all, since October 19, the Carney alone has intercepted at least 38 Houthi drones and anti-ship missiles (a mixture of ballistic and cruise types), according to CENTCOM media releases.

To date, however, the only type of ship-launched missile confirmed to have been employed by the U.S. Navy in the course of these operations is the less advanced and cheaper SM-2.

The USS Carney fires an SM-2 surface-to-air missile at a Houthi threat while sailing in the Red Sea on October 19, 2023. U.S. Navy

Details of the latest engagement were provided by U.S. Central Command (CENTCOM), as we reported last night, although the missile type(s) involved were not initially mentioned.

The command said the USS Carney shot down a Houthi ASBM at 8:30 PM local time before shooting down three “Iranian drones” in the warship’s vicinity at 9:10 PM local time. It’s unclear if those drones were actually operated by Iran, or were Iranian-designed but used by the Houthis. Soon after, CENTCOM announced a new round of U.S. strikes against a Houthi drone site in Yemen.

As for the SM-6, The War Zone has discussed this highly flexible missile in the past. As multi-purpose weapons, the Block I and Block IA versions currently in use can be employed against a wide variety of aerial threats. It also has a secondary capability against ground and surface targets. The SM-6B Block IB variant, which is currently in development, is expected to offer hypersonic speed itself and therefore have greater capabilities against hypersonic threats, and increased range.

An SM-6 round is loaded into a specialized container at the Raytheon Redstone Missile Integration Facility for delivery to the U.S. Navy. Raytheon

The SM-6 can also be used within the Cooperative Engagement Capability (CEC) package, which allows targeting information to be received from other offboard sources. The Navy long ago demonstrated the ability of ships to engage targets they cannot directly ‘see’ with their own sensors, using SM-6 missiles with the help of data provided by aircraft flying above. Meanwhile, carrier-based E-2 airborne early warning and control (AEW&C) aircraft — an important CEC asset — are known to be supporting anti-Houthi operations, and aircraft have also shot down cruise missiles in the course of the current campaign. We don’t know the extent to which this kind of networking is being used, but we certainly know this is a multi-layered effort.

For now, it’s also unclear exactly how the engagement of the ASBM played out, or even how many SM-6s might have been used to bring it down.

What may be critical, however, is the fact that the SM-6 is capable of engaging ballistic missiles — including ASBMs — in addition to separate re-entry vehicles and, in some instances, more novel hypersonic threats, and all in the terminal stages of their flight.

This Sea-Based Terminal capability, as the Pentagon describes it, was introduced to the SM-6 under the Dual I program.

A diagram of the SM-6, which is alternatively designated RIM-174 Standard ERAM (Extended Range Active Missile), shows how it makes use of components from other missiles. Missile Defense Agency

The SM-6’s seeker and terminal guidance electronics leverage technology developed for the AIM-120 Advanced Medium-Range Air-to-Air Missile (AMRAAM). However, the legacy semi-active radar homing capability from the Standard Missile family is also retained. Therefore, as well as short- and medium-range ballistic missiles in their terminal phase of flight, the SM-6 can still be used against anti-ship cruise missiles and all types of aircraft.

In contrast, the SM-3 is a dedicated ballistic missile interceptor that can engage intermediate-range ballistic missiles (IRBM), as well as hit shorter-ranged ballistic missiles in the middle portion of their flight. This is known as mid-course intercept capability. However, the SM-3 is not necessarily able to intercept certain shorter-range ballistic missiles, which fly at lower altitudes, and which could include ASBMs.

SM6 Launch Valiant Shield
The Arleigh Burke class destroyer USS Fitzgerald (DDG-62) launches a Standard Missile-3 (SM-3) as part of a joint ballistic missile defense exercise. U.S. Navy USN

While we don’t know what kind of ASBM was involved in the incident yesterday, the Houthis operate a wide range of ASBMs and quasi-ASBMs, including some converted from old Soviet-era SA-2 Guideline surface-to-air missiles. Most are of Iranian design, with the largest being the Asef, roughly 30 feet long and derived from the Fateh-313 short-range ballistic missile.

As we have discussed in the past, most Houthi ASBMs are firmly at the low end of the capability spectrum, meaning they fly at lower peak altitudes and lower speeds. In the past, this may have allowed the Navy to tackle them using SM-2 variants, with their limited terminal ballistic missile intercept capability.

Asef anti-ship ballistic missile on parade in Yemen in 2022. via X

It remains unclear why the far more advanced and expensive SM-6 was called upon yesterday, but this weapon has previously demonstrated its ability to intercept short-range and medium-range ballistic missile targets in their terminal phase, as you can read about here.

Perhaps not surprisingly, there has been plenty made of the discrepancy in cost between a single SM-6 missile and a Houthi ASBM.

The destroyer USS John Paul Jones (DDG-53) launches an SM-6 during a live-fire test of its Aegis weapons system, on June 19, 2014. U.S. Navy

While we don’t know the price tags of the kinds of ASBMs used by the Houthis, the cost of an SM-6 is around $4.2 million. This kind of mismatch is nothing new in today’s conflicts, of course. Other examples include using high-end air defense systems to destroy one-way attack drones over Ukraine or Saudi Arabia’s efforts also against Houthi drones and missiles. Considering the missile is protecting a ship that is worth over $2B and is packed with sailors, the cost to defend it is moot.

Moreover, the engagement has demonstrated that the U.S. Navy can respond to the kinds of ballistic missile threats that proliferate around the world. Most notably, China, Iran, and North Korea are also actively developing increasingly capable weapons in this class. The subclass of ASBMs is a particular worry, with China’s activities in this regard providing new ways for the People’s Liberation Army to engage large maritime targets, such as aircraft carriers, over great distances. The fast-growing need for naval ballistic missile defense, more generally, is something we have discussed at length only very recently.

The multirole nature and inherent flexibility of the SM-6, including its terminal intercept capability, have made it a critical capability for the foreseeable future. Outside of the Navy, the U.S. Army will also increasingly rely on the SM-6, which it is introducing as part of the Typhon Weapon System. This is a ground-based missile launcher that can fire both the multi-purpose SM-6 and the Tomahawk land-attack cruise missile.

For the time being, if the report is accurate, the SM-6 has now been combat-proven — critically, against a ballistic missile threat — which will only improve its already impressive credentials.

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