USS Maryland, a ballistic-missile submarine, returns to homeport at Naval Submarine Base Kings Bay, Ga.

USS Maryland, a ballistic-missile submarine, returns to homeport at Naval Submarine Base Kings Bay, Ga. U.S. Navy / Mass Communication Specialist 1st Class Ashley Berumen

ICBM Advocates Say US Missile Subs Are Vulnerable. It Isn’t True

Recent technological advances still favor the sea-based leg of America’s nuclear triad.

In recent years, as pressure has mounted against the Ground-Based Strategic Deterrent—the replacement program for the United States’ intercontinental ballistic missiles—ICBM advocates have deployed a familiar refrain. Relying primarily on nuclear-armed submarines for deterrence is too risky, they say, because “new technology and enemy efforts” will likely make U.S. submarines suddenly vulnerable to attack. 

This claim does not hold water. Not only are fears of a “transparent ocean” dramatically overhyped, but even if they were true, it would not affect the United States’ ability to maintain a credible second-strike capability––even without ICBMs.

As the Pentagon itself acknowledges, the United States’ Ohio-class SSBNs are among the quietest missile submarines on the planet. As the 2018 Nuclear Posture Review states, “When on patrol, SSBNs are, at present, virtually undetectable, and there are no known, near-term credible threats to the survivability of the SSBN force.” This is not the case for other nuclear-armed states’ missile submarines: Russia’s SSBN fleet is noisier than its American counterpart, and China’s Type 094 SSBNs remain noisy enough that analysts have questioned their survivability writ large. 

The next generation of U.S. SSBNs––the Columbia class––is expected to be even quieter than the Ohios. Instead of using the current submarine class’ noisy mechanical gears, the new submarines will be propelled by an electric motor. According to the Congressional Research Service, this will make the boats not just quieter but more survivable. Electric drive systems have more built-in redundancy, CRS has noted in reports to Congress, “making it less likely that a single weapon might disable the entire drive system.”

Despite these actual technological breakthroughs on the U.S. side, ICBM advocates often focus on an opposing kind of breakthrough: the hypothetical kind, that would allow nuclear-armed adversaries to sink or disable U.S. boomers at sea. 

These fears appear to be exaggerated, in several key respects. 

First, technological development is slow and does not occur in a vacuum. As Owen R. Cote Jr. has written, the U.S. Navy maintained a tremendous technological advantage over its Soviet counterpart during the Cold War by specifically working to “solve the [anti-submarine warfare] problem against its own submarines.” This continuous game of cat and mouse between submarine-quieting and submarine-detection technologies has allowed the United States to stay ahead of its competitors, who have historically not invested in these efforts to the same extent. 

As a result, if a game-changing technological breakthrough were to occur, the United States would, in all likelihood, be the one developing it. When the United States deployed the Cold War-era Sound Surveillance System––an underwater system of passive acoustic surveillance systems commonly referred to as SOSUS––the oceans did become relatively “transparent,” but only for one country. Since the United States was the only one pursuing such technology, the United States exclusively reaped the benefits. Today, given that the United States remains the leader in both submarine-quieting and -detection technologies, it is fair to suggest, as Cote Jr. did last year, that “no countries other than the United States have the global presence and the full spectrum of anti-submarine warfare capabilities needed to make even very quiet submarines potentially vulnerable.”

Additionally, fears of a “transparent” ocean often fail to consider the United States’ uniquely favorable geographical position relative to that of its nuclear-armed rivals. When U.S. submarines leave their ports, they are able to operate in a relatively uncontested manner, given the presence of allied ports and absence of territorial chokepoints that would constrain their patrol lanes. By contrast, Chinese SSBNs are seriously hampered by geographic limitations and cannot bring themselves within range of the continental United States without either developing longer-range missiles or sailing through dangerous chokepoints currently controlled by the U.S. Navy. 

Finally, even if an adversary were able to detect, track, and target a U.S. ballistic missile submarine, destroying it is another matter entirely. Assuming that an adversary were to target the United States’ SSBN ports in the opening stages of a nuclear conflict, that would likely only disable six of the 14 U.S. SSBNs at a maximum, as eight or nine SSBNs are typically at sea at any given time, and four or five of those are on “hard alert” and ready to fire at a moment’s notice. Even if an attacker were able to pinpoint the locations of every single one of these submarines, the requisite patrol aircraft, surface combatants, and attack submarines needed to destroy them would face significant logistical challenges––particularly U.S. air and sea defenses––and probably wouldn’t be close enough to do so before U.S. SSBNs would fire their own nuclear missiles in retaliation. 

In a 2018 article for Lawfare, Austin Long explains in more detail why destroying a submarine is harder than it looks––even with nuclear weapons. An adversary would have to fuze its missiles to withstand a high-velocity impact with the ocean, then detonate at depths of 100 or more feet, which Long describes as “a costly engineering challenge.” On top of that, he writes, the overpressure required to actually sink a submarine with a nuclear weapon is significant; perhaps nothing short of a one-megaton warhead could reliably do the job. 

When it comes to submarine invulnerability, the odds are clearly stacked in the U.S.’ favor. To that end, it is worth questioning why vague and fearful arguments about “transparent oceans” are receiving so much airtime of late, when they do not stand up to much analytical scrutiny. 

In reality, these claims are being made in service of an entirely different argument––one that has little to do with submarines at all, and everything to do with land-based missiles. Pressure is mounting on the incoming Biden administration to delay or cancel the Ground-Based Strategic Deterrent, with a growing number of former military officials, past defense secretaries, congressional committee chairs, and prospective cabinet picks openly questioning the need for a $260 billion investment in a relatively redundant missile system. 

The arguments in favor of pursuing GBSD are paper-thin, as evidenced by the fact that many ICBM proponents are increasingly forced to deride the Navy’s nuclear systems in order to justify their own. This pattern is decades-old, and has been well-documented by the Government Accountability Office, which noted in 1993 that “unsubstantiated allegations about likely future breakthroughs in Soviet submarine detection technologies, along with underestimation of the performance and capabilities of our own nuclear-powered ballistic missile submarines” are “used frequently as a justification for costly modernizations in the other legs to ‘hedge’ against SSBN vulnerability.” 

As the GAO’s assessment concludes, “[S]ubmerged SSBNs are even less detectable than is generally understood, and that there appear to be no current or long-term technologies that would change this. Moreover, even if such technologies did exist, test and operational data show that the survivability of the SSBN fleet would not be in question.” This reality still holds true today. 

Matt Korda is a Research Associate for the Nuclear Information Project at the Federation of American Scientists, where he coauthors the Nuclear Notebook with Hans Kristensen. Previously, he worked for the Arms Control, Disarmament, and WMD Non-Proliferation Centre at NATO headquarters in Brussels. He received his MA in International Peace and Security from the Department of War Studies at King’s College London. 

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