The U.S. Missile Defense Agency (MDA) has confirmed that, for the first time, a Standard Missile 3 (SM-3) Block IIA interceptor successfully destroyed an intercontinental-range ballistic missile (ICBM) target in a test. With this milestone, the SM-3 Block IIA becomes only the second U.S. interceptor type to exhibit this capability. The consequences for strategic stability and future arms control are serious.
Since the late 1990s, U.S. homeland missile defense efforts have been scoped around defending the country from a “limited” ballistic missile threat from North Korea and Iran. Earlier post–Cold War efforts focused on a wider range of potential threats. Because Iran does not currently possess an ICBM capability, the nominal threat today concerns North Korea, which has conducted three ICBM tests involving two separate missile designs.
Beyond North Korea, however, Russia and China have long expressed concerns that the United States seeks to counter their capacity to use ICBMs against it. These concerns have intensified since the United States in 2002 withdrew from the 1972 Anti-Ballistic Missile Treaty. The 2019 U.S. Missile Defense Review (MDR) notes that the United States “relies on deterrence” (as opposed to missile defense) to protect the homeland against “Russian and Chinese intercontinental ballistic missile threats.” But officials in both countries have expressed concerns that U.S. homeland missile defense efforts undermine their strategic nuclear deterrents.
They have reasons to think this. U.S. President Donald Trump remarked during the launch of the MDR that the core U.S. missile defense objective is to “ensure that we can detect and destroy any missile launched against the United States—anywhere, anytime, anyplace.” The president’s former national security adviser, John Bolton, similarly cited China as “one of the reasons why we’re looking at strengthening our national missile defense system here in the United States.”
What Was Tested
On November 16, 2020, a U.S. Navy Arleigh Burke–class guided missile destroyer, USS John Finn, launched an SM-3 Block IIA interceptor—a missile designed to quickly ascend from the earth’s surface and kinetically strike ballistic missile reentry vehicles outside of the earth’s atmosphere, using what is known as hit-to-kill technology. Minutes earlier, a target missile emulating an ICBM launched from the Marshall Islands’ Kwajalein Atoll in the southern Pacific toward open ocean northeast of Hawaii. USS John Finn’s Aegis Ballistic Missile Defense System (BMD), according to MDA, used an “engage-on-remote” capability, using off-ship sensors, to coordinate the interceptor launch. The test, with the mission name FTM-44, was successful in destroying the incoming “ICBM-representative target.”
Though the MDA has not clarified the nature of the specific target missile, distances between Kwajalein Atoll and the Pacific Ocean northeast of Hawaii fall short of the roughly 8,000 kilometer (5,000 mile) distance between North Korea and Hawaii, and the similar distance between North Korea and the northwestern United States (the shortest distance between a notional ICBM launch site in North Korea and a target in the 48 contiguous U.S. states). Because missile reentry vehicle speeds increase with range, this test would not have been appropriately representative of a North Korean ICBM. Moreover, the target missile likely did not incorporate sophisticated, or even rudimentary, countermeasures or other missile defense defeat measures, including multiple warheads.
Overall, the November 16 test marks just the third successful demonstration of a U.S. hit-to-kill BMD interceptor against what the MDA describes as a “threat-representative” target. The Ground-based Midcourse Defense (GMD) system—the only U.S. missile defense system built from the ground up to address ICBM-class threats—has succeeded twice in such tests (FTG-15 on May 30, 2017, and FTG-11 on March 25, 2019).
FTM-44 was a congressionally mandated test—motivated in part by North Korea’s demonstration of an ICBM capability in 2017. The MDA had earlier suggested that the Block IIA variant of the SM-3 missile would be capable of defeating ICBM threats. Later, the MDA explicitly denied that the Block IIA interceptor was designed to manage ICBM-class threats.
Rattled by North Korea’s rapid missile advancements in 2017, the U.S. Congress took action, guiding the MDA to explore the SM-3 Block IIA adaptability to ICBM threats. Section 1680 of the 2018 National Defense Authorization Act directed the MDA to “evaluate and demonstrate, if technologically feasible, the capability to defeat a simple intercontinental ballistic missile threat using the standard missile 3 block IIA missile interceptor.” Earlier testing of the missile focused nearly exclusively on medium- and intermediate-range threats. The 2019 MDR reiterated plans for the SM-3 Block IIA’s adaptation for a counter-ICBM role, describing it as an “underlay” for GMD that may “ease the burden” on that troubled system. Thus, the FTM-44 test represents a realization of a latent capability, at the direction of Congress, following the first North Korean ICBM flight-tests in 2017.
What Changes Now?
Just like their counterparts in Washington, officials in Moscow, Beijing, and even Pyongyang plan for the future and prepare for worst-case scenarios. With FTM-44 having considerably reduced doubts about the SM-3 Block IIA’s ability to manage ICBM-class threats, these countries will reason that any U.S. Navy destroyer is nominally capable of destroying an ICBM. Moreover, they may reason that any U.S. installation featuring a Mark 41 Vertical Launch System (VLS)—the physical canister that hosts the SM-3 Block IIA and a range of other air defense, BMD, and land-attack missiles—has such a capability. This could include the Romania- and Poland-based Aegis Ashore sites where the United States, through NATO, operates missile defense systems to protect Europe and North America. (As implied by the name, Aegis Ashore transports the ship-based sensors, computers, and software suites to a fixed, land-based installation.)
The Mark 41 VLS alone, without the support of the full Aegis BMD system, cannot amount to much, but this will hardly matter for the threat perceptions of U.S. adversaries. Moreover, even though the inventory of delivered SM-3 Block IIA interceptors remains low today, the available Mark 41 VLS inventory will likely inform threat perceptions in these countries. According to Lockheed Martin, the manufacturer of the Mark 41 VLS, at least 11,000 such cells have been delivered, including to ten non-U.S. navies (including several NATO allies).
Prior to FTM-44, a working assumption for these states might have been that the full scope of extant U.S. counter-ICBM capabilities was captured in the forty-four deployed GMD interceptors in Alaska. But the prospect of the new SM-3 Block IIA—and other possible interceptors—presenting a near-future threat to ICBMs has long been apparent. There are plans today to increase the number of deployed interceptors to sixty-four and develop a new kill vehicle for the GMD system, but the possibility of sea-mobile SM-3s with a counter-ICBM capability will likely, over time, erode GMD’s centrality to concerns in Russia, China, and North Korea—especially after the FTM-44 demonstration.
Despite U.S. adversaries’ worst-case perceptions, there are serious limitations to the ship-based BMD mission. Firstly, viable intercepts require the vessel hosting an SM-3 Block IIA interceptor to be positioned appropriately. In the case of the SM-3 Block IIA, an Aegis BMD–equipped destroyer would need to position for an exoatmospheric intercept in the descent phase of the missile’s reentry vehicle. Even though the SM-3 Block IIA covers a wide swathe of territory, vessels carrying the missile may not be appropriately positioned at all times. While, in a crisis, the U.S. Navy may be able to divert some destroyers to undertake a BMD mission by positioning for a North Korean ICBM launch, for example, this will not be possible in all cases.
Second, because Mark 41 VLS cells are a finite resource, assigning SM-3 Block IIA interceptors will come at the opportunity cost of these ships being able to undertake a strike mission, which may bear on pre-war deterrence in certain scenarios. As James Acton notes, other missions for Arleigh Burke destroyers, such as supporting and defending U.S. aircraft carriers, may similarly suffer. The U.S. Navy does not currently have an at-sea reload capability for these VLS cells, limiting the flexibility of these ships once their cells have been filled prior to deployment.
Finally, ship-based Aegis BMD will face challenges universal to all ballistic missile defense systems in coping with future ICBM threats. Unlike the near-idealized conditions under which FTM-44, FTG-15, and FTG-11 were conducted, adversary ICBMs may launch in large numbers and with countermeasures designed to defeat missile defenses. Even a comparatively less sophisticated adversary like North Korea will be capable of developing rudimentary countermeasures.
Future Arms Control and Strategic Stability
For years, Russian and Chinese officials have made little secret of their interest in addressing U.S. homeland missile defense capabilities in future arms control negotiations or dialogues on strategic stability. Even as the U.S. record on missile defense has been imperfect, Moscow and Beijing fear the potential for an overnight qualitative breakthrough that may seriously upend their confidence in their nuclear delivery capabilities. Washington has not reciprocated this interest in limiting missile defenses, seeking to maintain its freedom of maneuver on what is seen as a core national defense priority. In this context, FTM-44 marks a qualitatively significant milestone that will bear on future dialogues.
Strategic stability frays as states grow concerned that their adversaries seek absolute advantage. Even if ship-based ballistic missile defense remains niche and focused on North Korea, Russia and China fear that the United States will seek to attain first-strike capabilities against them, with BMD assisting in limiting the damage that might result from retaliatory strikes from Russian and Chinese missiles that may survive a U.S. first strike. Instead of promoting mutual vulnerability, which would in turn enhance stability, U.S. missile defenses are viewed as destabilizing.
Apart from Russia and China, even North Korea takes an interest in U.S. homeland missile defense capabilities—unsurprisingly so, given that it is portrayed as the primary threat by U.S. planners. In April 2019, North Korean leader Kim Jong Un remarked on FTG-15—the March 2019 counter-ICBM test—as yet another example of U.S. “hostile moves” against the country. North Korea’s unveiling of a new large road mobile ICBM—one perhaps suitable for multiple reentry vehicles—suggests that Pyongyang has already been planning to defeat missile defenses.
The United States already fears an arms race with Russia and China, both of whom have invested in technologies that should enhance their ability to penetrate U.S. counter-ICBM capabilities—today and tomorrow.
To avoid this mutually undesirable arms race, the United States should take Russian and Chinese concerns seriously and address them in good faith. Additionally, unilateral gestures, such as a declaration by the president of the United States that the sole purpose of U.S. nuclear weapons will be to deter nuclear war, may have value in reducing Russian and Chinese concerns about a U.S. first strike. Separately, by adopting an arms control approach to reducing nuclear risks with North Korea, the United States could consider capping homeland missile defense capabilities at current levels in exchange for a freeze on Pyongyang’s strategic missile production.
Ultimately, the consequences of the technical demonstration in FTM-44 will be challenging to reverse. This genie has left the bottle and the consequences for future arms control and strategic stability will be significant.