A new nuclear-armed, sea-launched cruise missile: Just say no

As can be seen in the headlines, the House of Representatives recently passed their version of the National Defense Authorization act, laden with provisions to fight “wokeness” in the military. This will create difficulties for reaching agreement with the Senate on a final bill. However, lost in the headlines is the fact that Congress will have to decide whether to fund the development of a new nuclear-armed, sea-launched cruise missile (acronym: SLCM-N) and its associated warhead. Based on its 2022 Nuclear Posture Review, the Biden administration zeroed out funding for this system in its budget request for 2024, but both the House version and Senate Armed Services Committee’s version of the National Defense Authorization Act authorize funding for the development of SLCM-N and its warhead. There are, nonetheless, multiple steps ahead to the point of actually appropriating funds (through appropriations bills), and so there are still real opportunities for informed decision-making.

A policy debate^[1] is raging about the development and deployment of the new nuclear-armed sea-launched cruise missile. Advocates^[2],[3] argue that in a world where the United States and Russia are in a state of extreme tension, and China is increasing its nuclear arsenal, the United States needs to strengthen its nuclear weapons capabilities, particularly at the so-called “middle rung” of deterrence, between so-called “tactical” and “strategic.” Those who oppose the new cruise missile^[4],[5] often argue that it is redundant and costly and will create practical impediments for the US Navy’s conventional war-fighting capability. Their arguments are cogent, but the situation is even worse than this. Deployment of such a weapon would seriously deteriorate, not improve, US national security and that of its allies, for reasons touched on in an article in Defense One^[6] and a fact sheet by the Physicists’ Coalition for Nuclear Threat Reduction.^[7] I flesh out these arguments here.

From a top-level perspective, at a time of increased tensions, renewed efforts at arms control and restraint are most needed. It is important to pull the most incendiary logs off the fire first, as President Reagan recognized in signing the Intermediate-range Nuclear Forces (INF) treaty in 1987. Now is not the time to add especially flammable fuel to the fire. Much worse than being redundant and costly, the sea-launched cruise missile is extraordinarily dangerous, having even more risky characteristics than the low-yield W76-2 warheads loaded onto submarine-launched ballistic missiles following the Trump administration’s 2018 Nuclear Posture Review.

There are at least three strongly compelling reasons that the SLCM-N is dangerous to US national security:

• To an adversary, a SLCM-N is indistinguishable from a conventional sea-launched cruise missile, so the very existence of the SLCM-N makes the use of a conventional SLCM a possible trigger for thermonuclear war, due to misattribution of a conventionally armed missile as one carrying a nuclear warhead. Since the Baltic and Black Seas are only 500 miles from Moscow and the Yellow Sea is only 500 miles from Beijing, with Taiwan about 1,000 miles from Beijing, stealthy SLCM-Ns with a range of 1,500 miles would create the risk for Moscow and Beijing of an undetected decapitating nuclear strike, and as a result create for the United States enhanced risk of disastrous split-second miscalculation by its potential adversaries. This is what the Intermediate-range Nuclear Forces Treaty was designed to mitigate, and what the current restraint on intermediate-range nuclear missiles in Europe is continuing. The United States would be throwing explosive logs onto an already hot fire with the SLCM-N.

Conventional Tomahawk sea-launched cruise missiles were employed in 1991 during the Persian Gulf War. Misattribution was not a significant risk, as Kuwait is nearly 2,000 miles from Moscow, and relations at the time between the United States under President George H.W. Bush and the Soviet Union under President Gorbachev were favorable. After President Bush removed all nuclear-armed sea-launched cruise missiles from service in 1992, conventional Tomahawk cruise missiles were used in Iraq, Bosnia, Afghanistan, Sudan, Yugoslavia, Somalia, Yemen, Libya, and Syria^[8] without any risk of misattribution.

NATO’s defense of Poland, Lithuania, Latvia, and/or Estonia would likely require the use of barrages of conventionally armed sea-launched cruise missiles. This would render misattribution by Russia an existential risk for the United States. Crucially, the deployment of SLCM-Ns would reduce, not enhance, the United States’ ability to defend its NATO allies.

• More generally, any use of a sea-launched cruise missile would be extraordinarily ambiguous; an adversary could not know whether it carried a conventional or nuclear payload, or, if the warhead were nuclear, what its yield might be. Greatly enhancing this ambiguity is an adversary’s inability to know where a stealthy, maneuverable cruise missile is headed, even if it is detected after launch. The SLCM-N blurs the escalation ladder in an extraordinarily dangerous way, through wide ambiguity in both its yield and its target.

The ambiguity is even worse than that which surrounds a submarine-launched ballistic (not cruise) missile armed with a low-yield W76-2. This missile certainly carries a nuclear warhead, and its trajectory can be determined. Because this submarine-launched missile is ballistic, adversaries will know in advance if it is headed to a strategic target in Moscow or Beijing, or to a battlefield tactical target.

• Arms-racing is now a three-player game. The United States is planning to build 38 Virginia-class attack submarines, each of which could carry up to 16 SLCM-N’s, with a potential total of 608 warheads^[2], even ignoring the possibility that these missiles could be placed on surface ships. Assuming reasonably that both Russia and China would feel that they must match such increased firepower, the United States could eventually be facing twice as many additional warheads as it mounted.

Adding nuclear warheads is not a wise long-term strategy for US security in the modern threat environment. In a three-way arms race, while the United loses in a two-for-one ratio when it increases nuclear warhead numbers, it can gain by a two-to-one ratio if it negotiates warhead limitations or, better, reductions with Russia and China.

The bottom line is that a new sea-launched cruise missile will deteriorate US national security in both the short and the long term. Furthermore, the new three-peer nuclear arms environment we are facing provides a strong incentive for arms control, not for arms racing.

Notes

[1] https://crsreports.congress.gov/product/pdf/IF/IF12084

[2] https://www.heritage.org/defense/commentary/the-nuclear-sea-launched-cruise-missile-worth-the-investment-deterrence

[3] https://www.atlanticcouncil.org/in-depth-research-reports/issue-brief/strengthening-deterrence-with-slcm-n/

[4] https://carnegieendowment.org/2022/05/12/taxpayers-should-question-pitch-to-fund-another-naval-nuclear-weapon-pub-87120

[5] https://armscontrolcenter.org/fact-sheet-nuclear-sea-launched-cruise-missiles-are-wasteful

[6] https://www.defenseone.com/ideas/2021/04/biden-should-sink-new-nuclear-weapon/173473/

[7] https://physicistscoalition.org/wp-content/uploads/2023/04/SLCM-N-Fact-Seet-April-20-2023-FINAL.pdf?emci=dce192ed-0f0a-ee11-907c-00224832eb73&emdi=ea000000-0000-0000-0000-000000000001&ceid=

[8] https://en.wikipedia.org/wiki/Tomahawk_(missile)