By Kingston Reif, Travis Sharp, and Kirk Bansak
As the United States and Russia contemplate further bilateral reductions in nuclear warheads and delivery vehicles beyond those required by New START, attention must be paid to the composition of each country’s strategic arsenal of nuclear-armed bombers, land-based missiles, and submarine-based missiles.
To understand the stability that arms control helps foster and that makes the United States safer, one must consider the arguments traditionally made about the strengths and weaknesses of each leg of the nuclear triad.
AS OF 2011
• Unlike land- or sea-based missiles, bombers can be recalled after launch. In a crisis situation, this would enable the cancellation of a bomber strike after it had been ordered if new information emerged and/or the president changed his or her mind.
• Bombers can be dispersed from their bases quickly in order to survive a nuclear first strike. Thus, the president would not feel the pressure to “use or lose” bombers during a crisis. Such pressure might exist with immobile land-based missiles.
• Because bombers are recallable, scrambling them toward a potential target is a highly-visible way of demonstrating resolve to adversaries and allies without actually launching a nuclear weapon. Such a demonstration of resolve might deter a potential adversary and thus prevent war. Land- and sea-based missiles offer no analogous capability.
• Bombers offer an alternative to missiles in assuring strategic penetration. If a nuclear force were entirely deployed on missiles, that force might be neutralized – thus negating assured destruction and deterrence – by an adversary’s deployment of a workable missile defense system.
• U.S. bombers today are located at only three continental bases in Louisiana, Missouri, and North Dakota. The bomber force could therefore be significantly damaged by a surprise attack against only three targets.
• Because bombers can carry both nuclear and conventional payloads, during a crisis an adversary might suspect that a conventionally-armed bomber was actually carrying nuclear weapons, thereby encouraging an attack against the bomber or a preemptive nuclear strike.
• Instead of demonstrating resolve and deterring an adversary, scrambling bombers might actually exacerbate tension by rousing suspicion of an impending nuclear strike, thereby prompting further escalation.
• Though assured strategic penetration is vital to deterrence, the odds are vanishingly small that an adversary could ever deploy a missile defense system robust enough to stop 100 percent of incoming long-range missiles. The alternative penetration option offered by bombers may therefore be practically useless.
WHY PRUNE BOMBERS?
U.S. nuclear submarines and Russian land-based missiles are the most valued legs of each nation’s respective nuclear triad, making joint elimination of either leg unlikely in the near-term. In contrast, deployed Russian and U.S. bombers are outdated, and U.S. bombers are increasingly tasked with conventional missions, suggesting that reductions of nuclear-armed bombers may be a potentially palatable option for both nations.3
LAND-BASED INTERCONTINENTAL BALLISTIC MISSILES (ICBMs)
AS OF 2011
United States: 450 missiles w/ 500 warheads
Russia: 295 missiles w/ 1,007 warheads
• ICBMs are the most numerous delivery vehicles in both the U.S. and Russian triads, and they are geographically dispersed in hardened, underground silos.
• As opposed to bombers and sea-based missiles, which are bundled onto relatively few aimpoints and may be vulnerable to attack, the size, protectedness, and dispersion of ICBM forces makes them virtually impossible to destroy short of an all-out nuclear attack.
• Because an ICBM force can only be crippled through a large and unmistakable nuclear attack, ICBMs provide greater clarity about when a country is under attack and who the attacker is.
• According to the Congressional Research Service, the cost per delivery vehicle for U.S. ICBMs is approximately one-quarter what it is for bombers and submarines.4
• Despite large numbers and dispersion, ICBMs are still vulnerable to a disarming first strike because they are immobile and thus more easily targetable.
• Because ICBMs are more vulnerable, the president might feel pressure to “use them or lose them” in the event of a crisis. This pressure might lead to a rapid decision to launch ICBMs based only on receiving warning of an impending attack.5
WHY PRUNE ICBMs?
The inherent vulnerability of immobile ICBMs will always offer a prime target for an adversary. In a crisis, this vulnerability could place “use or lose” pressure on the president. If submarines and bombers can be relied upon to provide credible deterrence, ICBMs are unnecessary.
SUBMARINE-LAUNCHED BALLISTIC MISSILES (SLBMs)
AS OF 2011
United States: 14 submarines w/ a combined force of 288 missiles and 1,152 warheads
Russia: 10 submarines w/ a combined force of 160 missiles and 576 warheads
• Because of its dispersion, mobility, and concealment, an SLBM force is effectively invulnerable while at sea.
• The invulnerability of SLBMs not only offers the assured retaliatory capability that is the bedrock of deterrence, but also ensures that the president will not face the “use them or lose them” pressure presented by ICBMs.
• A 1993 Government Accountability Office study concluded “…that submerged [nuclear-armed submarines] are even less detectable than is generally understood, and that there appear to be no current or long-term technologies that would change this.”6 Non-acoustic detection technologies, such as green-blue lasers and magnetic anomaly detection, continue to advance but have yet to yield any breakthroughs.7
• There are only a limited number of nuclear-armed submarines on patrol at any given time. If an adversary developed a way to locate these submarines, a disarming first strike might wipe out a SLBM force by concentrating on relatively few aimpoints.
• An attack on a SLBM force might be difficult to attribute. Submarines (and bombers) could theoretically be destroyed through purposeful attrition by a nation seeking to gain nuclear dominance. However, submarines could also be destroyed through operational accidents or in an attack by a nation not seeking to gain nuclear dominance. These scenarios would create uncertainty about whether the submarine force was under deliberate attack and/or whether a nuclear first strike was imminent. Such uncertainty could lead to mistaken escalation and/or retaliation.8
WHY PRUNE SLBMs?
Nuclear-armed submarines remain the most survivable leg of the nuclear triad. While pursuing a policy of “minimum deterrence” might entail reductions to all three legs of the triad, a safe and secure SLBM force seems destined to remain the centerpiece of deterrence – especially in the United States – for years to come.
1. All U.S. nuclear forces data is from Robert Norris and Hans Kristensen, “Nuclear Notebook: U.S. Nuclear Forces, 2011,” Bulletin of the Atomic Scientists, http://bos.sagepub.com/content/67/2/66.full.pdf+html.
2. All Russian nuclear forces data is from Norris and Kristensen, “Nuclear Notebook: Russian Nuclear Forces, 2011,” Bulletin of the Atomic Scientists, http://bos.sagepub.com/content/67/3/67.full.pdf+html.
3. Stephen Cimbala, “SORT-ing out START,” Joint Forces Quarterly 55 (4th Quarter 2009), pp. 52-54,http://www.ndu.edu/inss/Press/jfq_pages/editions/i55/8.pdf.
4. Senate ICBM Coalition, The Long Pole of the Nuclear Umbrella (November 2009), p. 15,http://www.conrad.senate.gov/issues/statements/defense/0911_ICBM_White_Paper.pdf.
5. Ivo Daalder and Jan Lodal, “The Logic of Zero,” Foreign Affairs 87:6 (November/December 2008), pp. 85-86,http://www.brookings.edu/~/media/Files/rc/articles/2008/11_nuclear_weapons_daalder/11_nuclear_weapons_daalder.pdf.
7. See Jeremy Hsu, “Lasers Could Find Friend or Foe Submarines Underwater,” LiveScience.com (May 2009),http://www.livescience.com/technology/090525-laser-sonar.html; and Martin Edmonds, “Anti-Submarine Warfare: New Scenarios,” Global-Defense.com (2000), http://www.global-defence.com/2000/pages/antisub.html.
8. National Defense University and Lawrence Livermore National Laboratory, U.S. Nuclear Policy in the 21st Century (2001), p. 1.19, http://www.ndu.edu/inss/books/Books_2001/US%20Nuclear%20Policy%20-%20Nov%2001/USNPAF.pdf.